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INSTRUCTIONAL

INSTRUCTIONAL DESIGN
Instructional Design (also called Instructional Systems Design (ISD)) is the practice of maximizing the effectiveness, efficiency and appeal of instruction and other learning experiences. The process consists broadly of determining the current state and needs of the learner, defining the end goal of instruction, and creating some "intervention" to assist in the transition. Ideally the process is informed by pedagogically and andragogically (adult learning) tested theories of learning and may take place in student-only, teacher-led or community-based settings. The outcome of this instruction may be directly observable and scientifically measured or completely hidden and assumed. There are many instructional design models but many are based on the ADDIE model with the phases analysis, design, development, implementation, and evaluation. As a field, instructional design is historically and traditionally rooted in cognitive and behavioral psychology.
(en.wikipedia.org/wiki/Instructional_design)

Thinking About Instructional Design:
Instructional Design as a Process:
Instructional Design is the systematic development of instructional specifications using learning and instructional theory to ensure the quality of instruction. It is the entire process of analysis of learning needs and goals and the development of a delivery system to meet those needs. It includes development of instructional materials and activities; and tryout and evaluation of all instruction and learner activities.
Instructional Design as a Discipline:
Instructional Design is that branch of knowledge concerned with research and theory about instructional strategies and the process for developing and implementing those strategies.
Instructional Design as a Science:
Instructional Design is the science of creating detailed specifications for the development, implementation, evaluation, and maintenance of situations that facilitate the learning of both large and small units of subject matter at all levels of complexity.
Instructional Design as Reality:
Instructional Design can start at any point in the design process. Often a glimmer of an idea is developed to give the core of an instruction situation. By the time the entire process is done the designer looks back and she or he checks to see that all parts of the "science" have been taken into account. Then the entire process is written up as if it occurred in a systematic fashion.
Other Definitions of "Instructional" Words
Instructional System:
An instructional system is an arrangement of resources and procedures to promote learning. Instructional design is the systematic process of developing instructional systems and instructional development is the process of implementing the system or plan.
Instructional Technology:
Instructional technology is the systemic and systematic application of strategies and techniques derived from behavioral, cognitive, and constructivist theories to the solution of instructional problems.
Instructional Technology = Instructional Design + Instructional Development
Instructional technology is the systematic application of theory and other organized knowledge to the task of instructional design and development.
Instructional Development:
The process of implementing the design plans.
(www.coe.uh.edu/courses/cuin6373/whatisid.html)
Interpretation of Instructional Design
To begin, an instructional design model gives structure and meaning to an instructional design problem, enabling the soon to-be designer to negotiate his/her design task with a semblance of conscious understanding.
In the book Real World Instructional Design, some valuable information on Instructional Design (ID) is emphasized throughout chapter one by showing how to identify and solve Instructional problems and how people learn and design effective instruction. There is much to be learned and applied to succeed as practitioners. Several effective ways to accomplish any one design task in the chapter stand out: one is the most common design model; the ADDIE instructional design model. Intulogh uses this popular instructional design model to help their clients analyze their training needs, design and develop training materials, implement training, and evaluate its effectiveness.
Another way is the spiral model was defined by Barry Boehm in 1988. This model is not the first model to discuss iterative development, but it was the first model to explain why the iteration matters. Kathy Cennamo and Debby Kalk adapt this model for instructional design in their book Real World Instructional Design. Because this model of development combines the features of the prototyping model and the ADDIE model.
The original spiral model, known as the spiral lifecycle model, is comprised of 10 iterative steps which move software development to a higher and higher fidelity until it is completed. To applying this model to instructional design, Cennamo and Kalk simplify the process into 5 steps:
Even those ADDIE is the most common design model, there are a number of weaknesses to the model which have led to a number of spin-offs or variations, and this brings to the comparison of the ADDIE instructional design model with the spiral model presented by Cennamo and Kalk.
The value of a specific model is determined within the context of use. Like any other instrument, a model assumes a specific intention of its user. A model should be judged by how it mediates the designer’s intention, how well it can share a work load, and how effectively it shifts focus away from itself toward the object of the design activity. In the ADDIE model, each step has an outcome that feeds into the subsequent step. In the Spiral model the design and development efforts are applied at each phase of the project, with an eye toward the end goal of the project. Even more important, the ADDIE is sometimes criticized for being liner, systematic, constraining, or inflexible.
Another main point stressed in the chapter is how the spiral model and many other models exist for use by different levels of instructional designers and for different instructional purposes; however, the ADDIE instructional design model forms a roadmap for the entire training project.
This is quite an extraordinary chapter. It helps me understand that models are like myths and metaphors, helping us to make sense of our world. Whether derived from whim or from serious research, a model offers its user a means of comprehending an otherwise incomprehensible problem.
This chapter will be useful for finding additional information. What I have learned in this chapter has increased my knowledge in this area.
I like reading books that make me think long after I have read them, but I did not expect this first chapter to break off and find a place inside me, and it definitely did just that. Overall, I can see that there are several effective ways to accomplish any one design task.
Chapter 1 provided good references at the end. I wish there are more books like this.
(http://foanda.wordpress.com/2010/02/11/interpretation-of-instructional-design-and-explaining-the-addie-model-of-id-comparing-it-with-the-spiral-model-presented-by-cennamo-and-kalk)
INSTRUKTIONAL MODEL (pdf)

INSTRUCTIONAL ACTIVITY
Teaching and learning strategies (SBM) in its implementation using a single / several methods of teaching which is a tool and how to implement teaching and learning strategies with the teaching method itself is also a tool to achieve the learning objectives.
In the instructional activities of a teacher can choose a more appropriate and more effective use of a teaching and learning strategies. This effort is intended to create a system of teaching and learning environment that is effective, which refers to "active role" of students in teaching and learning.
As a frame of reference for understanding that can eventually serve as the basis for choosing and to determine which instructional procedures are appropriate in achieving instructional goals, the following are some aspects to consider:
1. Teacher-student settings in teaching and learning activities (KBM)
2. The structure of teaching and learning events
3. The role of teachers in the process the message
4. Message processing
5. Learning Objectives
6. Instructional model used

Instructional model are grouped into 4 families is:
a. Model of social interaction
b. Model processing / processing information
c. Model personal Ilumanistik
d. Model behavior / behavior modification

3 components of instructional activities:
1. Preliminary Components
Instructional activities which include activities in which motivation and aware of the purpose of study, students also directs the activities of this component can be created actualization activities with various procedures.
2. Presentation Components
Is a component of instructional activities which consist of activities to help process the information, get information from memory, and assist students during training. This component is the core component, where the teacher's role is to explain or describe the material to be learned, gives examples that are relevant and provide an opportunity to show the ability of students.

Actualization instructional activity below can be used as material consideration in determining the order of which procedure is used in the presentation of activities:
Procedure I:
Referred to as traditional or conservative procedure that begins with an understanding of concepts, principles or procedures, and followed by examples that are relevant in everyday life.
Procedure II:
The presentation begins with the provision of examples or cases to solve, followed by exercises and ends with a description or a generalization of the lesson content.
Procedure III:
The presentation was preceded by the provision of training or testing followed by a description which ended with an example.
Procedure IV:
The presentation begins with a description accompanied exemplification of the concepts, principles or procedures, and concludes with application exercises.
Procedure V:
The presentation begins with providing a description of the concepts, principles, procedures followed by exercises to learn to master it and ending with its application in practice of everyday life.
Procedure VI:
The presentation begins with a chance to try first and then followed by examples for comparison and concludes with a description or a conclusion.

3. Components cover
In this component of the teacher is still giving or applying the sequence of test activities and formative feedback to continue with follow-up activities in the form of guidance from teachers about what to do with respect to the results of student progress (learning achievement)




INSTRUCTIONAL OBJECTIVES
Selecting Instructional Objectives, Considering in Review (Part 3)
Selecting Instructional Objectives, Considering in Review (Part 3)

Are the instructional objectives in harmony with basic principles of learning?
As indicated earlier (in Selecting Instructional Objectives, Considering in Review part 1 and Selecting Instructional Objectives, Considering in Review Part 2), our instructional objectives should be stated as desired learning outcomes. Thus, it is legitimate to ask to what extent our instructional objectives are in harmony with what is known about the principles of learning. Some of the basic factors that should be considered are the following:

Readiness
Are the students mature enough to attain these particular instructional objectives? Do the students have the necessary experiences and educational background to proceed successfully? Is there another level at which some of the objectives might be attained more readily?
Motivation
Do these particular instructional objectives reflect the needs and interests of the students? Can they be restated or modified to be more closely related to students’ concern? Is there another stage of development where these objectives would more closely fit the students’ emerging interests?
Retention
Do these particular instructional objectives reflect learning outcomes that tend to be retained longest (e.g., understanding, application, thinking skills)? Are there other objectives that might be more lasting and that should be included?
Transfer Value
Do these particular instructional objectives reflect learning outcomes that are widely applicable to new situations? Do the objectives include methods of study and modes of thinking that are most likely to contribute to future learning in the area? Do these objectives reflect realistic and complex learning tasks that are most useful in the “real” world?
These questions are not always easily answered, but they highlight the importance of considering the learning process when we formulate and select instructional objectives. Most general textbook on educational psychology will provide extended discussions of the basic learning principles. It is sufficient to point out here that the more complex learning outcomes tend to be retained longer and to have greater transfer value. When they are appropriate to the developmental level of the learner, the more complex outcomes also have the greatest potential for arousing and maintaining student interest.
(http://fromlearningtoteaching.blogspot.com/2008/05/selecting-instructional-objectives_4222.html)


LESSON PLAN

Lesson Plan (A)
What is a lesson plan
A lesson plan is a teacher's detailed description of the course of instruction for an individual lesson. A daily lesson plan is developed by a teacher to guide class instruction. Planning the material is much more difficult than delivering the lessons. Planning is when you look at the curriculum standards and develop the content that match those standards you also have to take into consideration the needs of the children you are planning for. Luckily, textbooks that are adopted for your subject areas are typically written with this in mind. All details should be written down to assist the smooth delivery of the content. The extent of the detail will vary depending on the number of years of experience that the teacher has and the number of times he/she has taught the lesson. Obviously, an instructor with several years of experience may have plans that are much less detailed than beginning teachers. There will be requirements mandated by the school system that employs you regarding your responsibilities.
While there are many formats for a lesson plan, most lesson plans contain some or all of these elements, typically in this order:
• Title of the lesson
• Time required to complete the lesson
• List of required materials
• List of objectives, which may be behavioral objectives (what the student can do at lesson completion) or knowledge objectives (what the student knows at lesson completion)
• The set (or lead-in, or bridge-in) that focuses students on the lesson's skills or concepts—these include showing pictures or models, asking leading questions, or reviewing previously lessons
• An instructional component that describes the sequence of events that make up the lesson, including the teacher's instructional input and guided practice the students use to try new skills or work with new ideas
• Independent practice that allows students to extend skills or knowledge on their own
• A summary, where the teacher wraps up the discussion and answers questions
• An evaluation component, a test for mastery of the instructed skills or concepts—such as a set of questions to answer or a set of instructions to follow
• Analysis component the teacher uses to reflect on the lesson itself —such as what worked, what needs improving
• A continuity component reviews and reflects on content from the previous lesson[1]
A well developed lesson plan
A well developed lesson plan reflects interests and needs of students. It incorporates best practices for the educational field. The lesson plan correlates with the teacher's philosophy of education, which is what the teacher feels is the purpose of educating the students.[2]
Secondary English program lesson plans, for example, usually center around four topics. They are literary theme, elements of language and composition, literary history, and literary genre. A broad, thematic lesson plan is preferable, because it allows a teacher to create various research, writing, speaking, and reading assignments. It helps an instructor teach different literature genres and incorporate videotapes, films, and television programs. Also, it facilitates teaching literature and English together.[2] School requirements and a teacher's personal tastes, in that order, determine the exact requirements for a lesson plan.
Unit plans follow much the same format as a lesson plan, but cover an entire unit of work, which may span several days or weeks. Modern constructivist teaching styles may not require individual lesson plans. The unit plan may include specific objectives and timelines, but lesson plans can be more fluid as they adapt to student needs and learning styles.
Setting an objective
The first thing a teacher must do is decide on the lesson plan's focus. The teacher creates one idea or question they want the students to explore or answer. Next, the teacher creates classroom activities that correlate with the established idea or question. This includes individual and group activities. Having established these activities, the teacher identify what language arts skills the lesson plan must cover. After the teacher completes these activities, they must ensure the lesson plan adheres to the best practices used in language arts. This includes conducting research on what teaching methods result in a high success rate for students. The teacher must ensure the lesson plan goals are compatible with the developmental level of the students. The teacher must also ensure their student achievement expectations are reasonable.[2]
Selecting lesson plan material
A lesson plan must correlate with the text book the class uses. The school usually selects the text books or provides teachers with a limited text book choice for a particular unit. The teacher must take great care and select the most appropriate book for the students.[2]



Types of Assignments
The instructor must decide whether class assignments are whole-class, small groups, workshops, independent work, peer learning, or contractual:
• Whole-class—the teacher lectures to the class as a whole and has the class collectively participate in classroom discussions.
• Small groups—students work on assignments in groups of three or four.
• Workshops—students perform various tasks simultaneously. Workshop activities must be tailored to the lesson plan.
• Independent work—students complete assignments individually.
• Peer learning—students work together, face to face, so they can learn from one another.
Contractual work—teacher and student establish an agreement that the student must perform a certain amount of work by a deadline.[2]
Testing
The teacher must decide how to evaluate each student's performance.[2]
Summative Assessment Summative assessment evaluates learning needs. It usually consists of tests, semester exams, end of unit or end of chapter tests that evaluate student progress, performance, and knowledge. The teacher calculates final grades based upon performance in these exams. These assessments may help teachers adjust future curriculum, based upon how well the students retain information.[3]
Formative Assessment Formative assessment evaluates the process of learning in its process, and is a part of the teaching process. Teachers use formative assessment to discover holes and modify their teaching and the learning of their students. In contrast to end-of-unit adjustments in a summative assessment program, formative assessment recognizes student needs in the course of learning. This approach lets educators adjust learning standards right away. By knowing each student's current needs, including those with lower abilities, a teacher can address them immediately. Teachers use formative assessment information to modify teaching and learning activities to improve learning results.[3]
Reliability of classroom assessment
Classroom assessment reliability is controversial. Teachers have different grading and evaluating standards. Some emphasize the amount of work, while others value quality. Formative and summative assessment procedures should be equally applied in the classroom. However, it seems the modern education system (see NCLB) puts more stress on summative assessment, and evaluates student performance mainly with exams. Summative assessments are easy, and provide an objective picture of the students’ skills and knowledge. However, applying classroom formative assessments more often provides current information about students’ learning needs.[3]
Evaluate the lesson plan
As mentioned above, a teacher must use best practices to ensure their students have a high success rate. Traditional methods of assessment may be used (quizzes and tests). This is also a time of reflection for the teacher. The student must learn from the lesson, as should the teacher. Find out what areas of the lesson didn't work as smoothly as projected and make adjustments.
Areas to Evaluate:
• Materials
• Content
• Engaging and Interactive
• Creativity
• Extension
• Presentation Skills
[2]
Unit of Instruction
A unit of instruction or "unit" is a collection of lesson plans all pertaining to the same topic. For example in a computer applications class a teacher could build all lessons dealing with Wordprocessor into a unit plan.
Lesson Plan as a Component of a Unit Plan
A unit plan is a series of lessons organized around a single theme, topic, or mode. The unit plan should provide the teacher with a concise overview of the unit, including information about art works, art materials, and special preparations that need to be considered. The unit should be organized to emphasize sequences of learning activities. [4]
Beyond Test Answers
Plan a cumulative lesson or activity to get students to higher levels of thinking. Often when creating units of instruction and individual lesson plans, we forget to assign a project that is hands on for the students. While it is important for students to know the definitions of terms, it is even more important for them to be able to use the information they have learned. Creating a unit on Investing and an individual lesson plan on the stock market is good, but integrating a stock market game for the entire unit of instruction is more valuable to the students and helps them understand the stock market at an application level.
A Computer Applications Unit Plan
This Unit Plan should be centered around a single topic (i.e. MS Word, MS Excel, MS Power Point, MS Access) and it will more than likely cover multiple weeks and be composed of multiple lesson plans. Student achievement should be clear and upfront. For instance, it is recommended that you put a daily objective on the white board everyday so that the students understand exactly what is expected for that day. It is also highly recommended that project based learning be utilized instead of using the textbook always. Students enjoy doing projects versus using textbooks and projects normally always keep the students engaged longer.
Student Outcome
Students will demonstrate knowledge of Spreadsheet by completing multiple practice assignments, answering short answer questions on quizzes and finally passing an Spreadsheet test with at least 80% accuracy.
Length of Unit
You will need to take some time and plan out how much time can be devoted to a unit. For example, in a nine month school year there are approximately 36 weeks. Make a list of the units you want to cover over that time period. From there break down how many days or weeks can be spent on each unit.
Definition of Unit of Instruction
The Plan of Instruction should contain everything which is pertinent to the specified course as it relates to the instructional needs of the student and the teacher. The plan should clearly describe who this course is for, how it is to be implemented, what is to be taught, and how satisfactory student performance is to be determined. The plan should be written with sufficient detail to enable a qualified reader to understand the intent of the writer.[5]
Unit Goals
Unit goals determine purpose, aim, and rationale for what you and your students will engage in during class. This section should be used to express the intermediate lesson goals that draw upon previous plans and activities and set the stage by preparing students for future activities and further knowledge acquisition. The goals are generally written as broad educational goals adhering to State or national curriculum standards. Many schools will also require that goals be simplified to a student friendly format. To begin, ask three basic questions: Where are your students going? How are they going to get there? How will you know when they've arrived? [6]

UNIT THEME
A thematic approach is a way of choosing an overarching or unifying idea revealing many aspects of related concepts, events, or situations. A theme is much broader than a topic, and use of themes in curriculum design allows students to make rich connections among a variety of disciplines. A topical approach is a way of organizing information regarding particular subject matter, and is narrower in focus. The following are all topical in approach rather than thematic: Elements and principles of design; Art modes and media; Periods of western art history; Art from various culture or eras; Aesthetics topics; Landmark art works or individual artists; Functions of art. [7]
Sample Unit Plan: Personal Financial Decisions
Lesson 1: Evaluate current position. Goal: Determine current financial assets and liabilities
Lesson 2: Set goals. Goals: 1) Establish short-term financial goals. 2) Establish long-term financial goals.
Lesson 3: Create a plan. Goal: Create a plan for accomplishing goals.
Lesson 4: Evaluate. Goals: 1) Evaluate effectiveness of plan in accomplishing goals. 2)Adjust plan as needed to better accomplish goals.
Examples of Units of Instruction
This unit plan of instruction example for a business law class:
Business Law Unit 3 Plan The Law of Sales
Teacher:
Unit Goals/Objectives: Students will: 1. Define sale and explain how the Uniform Commercial Code (UCC) governs the sale of goods. 2. Explain how the UCC treats unconscionable contracts and contracts of adhesion. 3. Compare the status of a casual seller with a merchant. 4. Explain how the Statute of Frauds is applied to sales. 5. Discuss who may transfer ownership of goods. 6. Explain requirements for ownership transfer. 7. Explain the general rules for identifying when risk of loss transfers. 8. Identify the point at which insurable interest of goods transfers. 9. Identify when risk of loss and insurable interest transfer in specific situations. 10. Explain the need for governmental involvement in the marketplace. 11. Identify protections against substandard goods. 12. Recognize unfair trade practices. 13. Identify the various warranties that may apply to a sales transaction. [8]
National / State Standards:
Section 2- Level 2 • Define goods and distinguish them from services and real property Section 2- Level 3 • Explain when to apply the law of sales and leases of goods under the Uniform Commercial Code (UCC) • Give examples of special rules that apply to sales contracts that do not apply to other contracts • Clarify when sales contracts must be in writing and state the exceptions • Judge whether a particular writing meets the requirements of the UCC for the sale of goods • Compare an auction with reserve with an auction without reserve Section 2- Level 4 • Explain when title and risk of loss pass in a sale of goods • Relate how express warranties, implied warranties, and the warranty of title arise, and describe how each of the warranties may be excluded or modified • Describe when the statute of limitations usually begins and ends in a sales transaction • State when a contract for the sale of goods must be evidenced in writing • List and define the performance obligations of the seller and buyer in a typical sales transaction and define the terms F.O.B., F.A.S., C.I.F., C.F., and C. & F. and state the legal consequences of using them
Competency Profile Competencies Covered: • Differentiate among the ways that assent can be disrupted, such as fraud, nondisclosure, misrepresentation, mistake, duress, and undue influence,3 • Explain the various rules applied to contracts involving third parties,3 • Discuss consumer protection legislation, such as the Federal Trade Commission Act, the Consumer Product Safety Act, and the Consumer Leasing Act,3 • Describe the various rules applied to the interpretation of contracts,3
Unit Lessons:
1. Sales Contracts a. Sales 1. What is a Sale? b. Special rules for sales contracts 1. Rules for merchants 2. Statute of Frauds
2. Ownership and Risk of Loss in Sales a. Transfer of Ownership 1. Who transfers ownership? 2. Requirements b. Risk of Loss and Insurable Interest in Sales 1. When does risk of loss transfer? 2. When does insurable interest transfer? 3. Rights and risks in specific sales
3. Consumer Protection a. Protection through Governmental Action 1. Inferior services and goods 2. Unfair trade practices b. Protection through Action by the Consumer 1. Product liability 2. Warranties [8]
Materials/ Resources/ Supplies Needed for Unit: • Computers/computer equipment/ Internet • Guest speaker (business owner in community) • Sample Contracts • Textbook • Newspaper articles/ Case studies • Documents for assignments and handouts • Documents for exams • Rubric and grading scales
• Two Outside Resources- Guest speaker and Sample Contract Documents - I want to bring in a local business owner to show how sales contracts work in the community. I will prep him/her on what we have been talking about so they can talk about how this unit relates to their work. Terms and topics that will be discussed are: sales, ownership, price, goods, use of credit, payment and delivery, acceptance of goods, merchant, transfer of ownership, sales on credit, warranties, bait and switch, and liability. - I also want to show the kids what contracts look like. They come in many variations. I found one way at http://smallbusiness.findlaw.com/business-forms-contracts/be8_9_1.html. I will ask our guest speaker to bring in any documents he/she uses as well. The students can see what the terms and obligations of a sale will include and what to look for when purchasing a product.
FBLA Integration: • FBLA has a competitive event called Business Law, which involves a one hour test. The test covers 13 competencies. This unit covers some of those competencies, including contracts, sales, consumer protection, and product and personal liability. To help prepare students for this test, I could give them a timed test, which would include questions covered throughout the course that relate to the FBLA event. This will give them an idea on what to expect when they participate in this event.
• Under business award is Activity 13, which is visiting and touring a business. I could set up a time for the class or a student to take a trip to a hardware or appliance store to see how the business is operated. Since this is a unit over sales contracts, the manager could show and talk about how they make sales transactions and sell their products. We could be able to see what forms they use and the terms and obligations they follow. Warranties are probably included with hardware and appliances, so we could ask about their policies towards them. Return policies can also be discussed.
Unit Evaluation/ Reflection/Comments: • Students will take formative and summative assessments for the unit plan. After the unit is completed, I will make notes of what worked well and what could be improved. Each lesson will be evaluated individually as well.
(http://en.wikipedia.org/wiki/Lesson_plan)
Lesson Plans (B)
The lesson plans in this section are intended to support teachers as they are thinking about the methods they use in order to meet the individual needs of their students. Lessons should be planned to engage students and to connect the activities with the mathematics content. Each lesson should have a clear goal, and every part of that lesson-from the opening activity to the final summary-should be goal-focused, helping to move students toward a clearer understanding of the concepts at hand. These lessons are designed to: actively engage students, make use of real-world situations, and connect the mathematics concepts with the concepts that students have already learned. We encourage you to build on these plans and tailor them to the needs of your students.
You will need to view these lesson plans.
Title Lesson Topic Grade Lesson Length
Can You Build It?
Perimeter 3 40 minutes
Can You Name That Shape?
Polygons 2-4 80 minutes
Find the Shape
Using ordered pairs to identify, locate, and plot points on the coordinate plane 4-5 40 minutes
Geoboard Squares
Squares and patterns 2-3 50 minutes
How Close Is Our Estimate?
Estimation and measurement 5 50 minutes
Investigating Nets and Polyhedra
Three-dimensional shapes and their nets 5 50 minutes
It's a 3-D World Out There!
Polyhedra 2-4 80 minutes
Reflections
Reflections and glide reflections 5 50 minutes
Rep Tiles
Creating similar shapes using a single shape 3 60 minutes
Rep Tiles
Creating similar shapes using a single shape 4-5 50-75 minutes
The Sum of the Interior Angles of a Polygon
Decomposing polygons into triangles to find a formula for the sum of the interior angles of a polygon with n sides. 4-5 50-75 minutes
Tiling the Plane
Tiling the plane with pattern blocks 2-3 30 minutes
Tiling the Plane
Tiling the plane with pattern blocks 5 50 minutes
Traveling around Our Town
Tracing a path on a grid from one location to another 1-2 30 minutes
Visualizing Multiplication
Area model for multiplication 3-5 50 minutes
(http://images.rbs.org/activities_plans/plans.shtml)

ASSESSMENT
Assessment
More than giving grades and ranking students, assessment is the gathering of evidence—about a student's knowledge of, ability to use, and disposition towards a subject—and then making inferences from this evidence. A teacher can use assessment as a tool to make instructional decisions, to support and enhance students' learning, and to answer the question: "How do I know what my students know?" The best instruments for assessment also increase students' knowledge and understanding.
Teachers need to strive to make assessment an ongoing, daily aspect of the teaching process, rather than an occasional interruption. Assessment should be appropriate to the conceptual levels/objectives of the lesson and be aligned with standards and with the instruction itself. For example, if students use manipulatives during instruction, then they should use them during the assessment as well.
Building an accurate picture of student performance in the classroom requires integrating a number of different ways to assess students' performance:
• Formative assessments help the teacher understand what the students know, do not know, and might need in terms of instruction. Ideally, these assessments are going on all the time as the teacher uses the feedback to enable students to learn better.
• Summative assessments, such as graded work, attempt to measure the quality of students' performance or to summarize student learning at some point in the course of a class.
• Assessments should be both formal (planned in advance with specific goals in mind) and informal (recording observations in the course of regular teaching).
• Assessments can be done before, during, and/or after a lesson.
Assessment standards are criteria for judging the quality of assessment practices. These embody a vision of assessment that is consistent with the curriculum and teaching standards derived from shared principles of mathematics, cognition, and learning.2 This section addresses the following assessment techniques and gives examples for how they are best represented in geometry and measurement:
• Observation
Observation is a direct means for learning about students, including what they do or do not know and can or cannot do. This information makes it possible for the teacher to plan ways to encourage students' strengths and to work on their weaknesses.
Observation is most effective when it follows a systematic plan. This might involve, for instance, seeing and recording which students use physical materials, which do most of the problems mentally, which use thinking strategies, and which rely on memorized facts.4 It may be helpful at times to focus on observing one student within the context of a group setting.
Observation tools are instruments and techniques that help teachers to record useful data about students' learning in a systematic way. Some observation tools include:
Anecdotal notes: Short notes written during a lesson, as students either work in groups or individually, or after a lesson.
Anecdotal notebook: A notebook where a teacher records his or her observations. An index on the side, organized by either student name or behavior, is helpful.
Anecdotal note cards: An alternative system to an anecdotal notebook, in which the teacher records observations using one card per child. One way to facilitate this process is to select five children per day for observation. The cards can be kept together on a ring.
Labels/adhesive notes: Like note cards, the use of these small adhesive notes frees the teacher from having to carry a notebook around the classroom. After the observation is complete, the teacher can adhere the notes into his or her filing system.
Sample observations
A checklist of possible behaviors to observe in students:
 names/identifies two-dimensional shapes
 sorts two-dimensional shapes using attributes
 identifies two-dimensional shapes in nature
 uses correct terminology to describe two-dimensional shapes
 uses concrete objects to join two shapes to make a new shape
 can use attributes to create shapes on a geoboard
• Questioning
Questioning is a way of teaching that actively invites students to convey what they are thinking. Good questions, prepared before a lesson, will help a teacher determine whether students use varied approaches to a problem and how well students can explain their own thinking. This process complements observation.
Another important aspect of questioning is waiting for students to respond. While the average time teachers wait for responses is less than three seconds, teachers should allow for more time for students to think through their responses.
Think-alouds are a teaching/assessment strategy in which one verbalizes his or her thought process. A teacher should incorporate this into the daily practice of teaching, modeling it first, and then encouraging students to try it as well. Think-alouds can be especially helpful in revealing how a student arrived at a particular answer.
Probing questions are a teaching/assessment strategy that provides insight into the mental processes a student is using by engaging him or her in conversation about the subject. The goal of the questions is to deepen the student's understanding of the content.
Sample probing questions
• How did you know that?
• What strategy did you use?
• Does that remind you of another problem we solved?
• Can you show us how you did that?
• Is there another explanation?
• Can that be done another way?
• What if I changed [some element of problem]?
Prompting questions are a process by which a teacher supports a student by giving hints that point the student toward appropriate strategies to use to solve a problem or to clarify his or her response. Prompting questions go far beyond simply making statements to students in the form of a question. It is important that teachers not "funnel," by either answering the question themselves or changing the question to one that requires little thought to respond.
Sample prompting questions
• Remember when we did [a past problem]?
• How would you begin this problem?
• What do you think this relates to?
• What are you thinking about this problem?

• Interviewing
Interviewing is an interaction in which a teacher presents a student with a planned sequence of questions and listens for answers. These exchanges can be a rich source of information about how the child is constructing concepts or using procedures, and they give the teacher direction for modifying instruction.
Interviewing is also beneficial when done student-to-student or within a group of students. The teacher should assign one student the role of interviewer, one the role of interviewee, and any others the role of observers. In student-student interviews, the teacher needs to provide leading questions and guidelines for interviews, including what to look for. The teacher can also play the role of observer, using observation strategies to gain insight into students' understanding.

Sample interview 8
(grades 3-5)
Display a collection of either two- or three-dimensional shapes. Select one shape that has something in common with more than one shape in the collection. Ask the student to select a shape that is like your shape in some way and to explain the choice. Observe whether or not the student uses visual cues or is able to use attributes. Ask the student to select another shape that is like your shape in some way and to justify that choice.
• Performance Tasks
Performance tasks are open-ended, multi-step problems that require students to apply information, understanding, and previous knowledge to create their own learning activity. These tasks should be designed carefully, both to engage students' intellect and to incorporate sound and significant mathematics. Ideally, performance tasks offer students time to investigate and grapple with a problem and to devise their own responses and explanations for how they arrived at an answer. It may be helpful to start with simpler tasks and work up to longer, more complex ones. Assigning students to work on performance tasks in pairs or groups of four will enrich the teacher's observations and notes about strategy, results, and attitude.
Teachers often evaluate performance tasks using a rubric, which is a hierarchy of performance standards and expectations. Whether task-specific or general, the rubric makes it possible to determine a student's score based on overall performance on a task, as opposed to simply the number of correct or incorrect items. A sample rubric could consist of a scale of three to six points that are used to rate performance. Rubrics can be shared with students to help to engage and empower them in the learning process.
Sample performance task
(grades 4-5)
Materials: Pattern blocks, paper, and colored pencils or crayons
Directions:
1. If the area of the green triangle is one square unit, find the area of the blue rhombus, the red trapezoid, and the yellow hexagon.
2. Use your pattern blocks to create two different designs with an area that is exactly 15 square units. Draw your patterns on the paper provided.
3. Write three observations about each of your designs.


Sample rubric for this task:
Points Performance
5 The student correctly determines that the area of the blue rhombus is two square units, the area of the red trapezoid is three square units, and the area of the yellow hexagon is six square units. The two designs have an area of exactly 15 square units, and the student's observations use correct geometric terms.
4 One of the areas is incorrect or the student uses a geometric term incorrectly.
3 Two or three mistakes are made in determining areas or using geometric terminology.
2 Four mistakes are made in determining areas or using geometric terminology.
1 Five or more mistakes are made in determining areas or using geometric terminology.
0 No work is shown or the work is not on task.
• Self-Assessment and Peer Assessment
Self-assessment is the process by which students evaluate their own work, given criteria established by the teacher. This is important because, ultimately, the responsibility for learning belongs to the student. A teacher might ask students to validate their thinking on certain problems or to explain how they arrived at a particular solution. It is important that a teacher asks about correct answers as well as incorrect ones, in order to support the idea that students have control of the subject and that questioning is not related to students' mistakes or failure. Student self-assessment helps to build students' self-esteem, and it helps them to see how incorrect answers can be valuable in the process of arriving at correct solutions.
Sample self-assessment
After students complete a mathematical problem or investigation, ask them to evaluate how they felt about their work by writing "yes," "no," or "not sure," in response to all of the following questions. Be sure to explain that there are no correct or incorrect responses.
I understood the directions to the problem. __________
I found an answer to the problem. __________
I could explain this problem to another student. __________
I enjoyed solving this problem. __________
I thought the problem was too hard. __________
I thought this problem was too easy. __________
I thought this problem was just right. __________
I never saw this kind of problem before. __________
This problem reminds me of other problems I have solved. __________
I would like to do more problems like this one. __________
• Work Samples
Work samples include projects, written assignments, and other student products that the teacher collects and evaluates. Scoring, which involves judgement, and analyzing the work make it possible to learn about student performance.
Possible work samples
• problems students have solved
• charts students have constructed
• journal entries
• written passages in which students explain the process by which they solved a problem, how to approach a problem, and/or how a problem is related to other activities in mathematics
• students' evaluation of "error patterns" in problems
• problems students have constructed themselves.
• Portfolios
A portfolio is a collection of a student's work over a period of time (a term, a year), which can be used for assessment by both the teacher and by the student. It can include special problem-solving tasks, writings, investigations, projects, and reports—even photographs of students working individually, in a group, or on a project. These items can be presented not only on paper but also on audio- or videotapes and/or computer disks.
By dating each of the entries, the student (and the teacher) can use the portfolio to see the growth of a body of work. Portfolios can be "learner-managed" (organized by the student), teacher-managed, or both, although a teacher of lower grade levels should give students specific directions as to how to organize their portfolios. It can also be valuable to give a student a portfolio project over consecutive years, in order to observe the evolution of that student's understanding.

• Writings
Students' writing, such as a journal or items included in a portfolio, is a valuable means of assessment. Writing projects can be as simple as asking students to describe what they learned in a particular day, what they like about mathematics, or what they did or did not understand about an assignment. A letter to a friend about mathematics class or a poem about triangles is a creative tool by which a teacher can assess students' knowledge of and attitudes about mathematics in general.
Journal writing is a series of writings in which a student reflects on his or her learning. Since journals can include diagrams, graphs, labels, and symbols, journal writing can be a more inclusive form of communication than an oral response. In many cases writing also deepens students' understanding because it requires them to organize their thoughts differently.
A teacher must respect the privacy of what students write in journals. Because the journal is not only a forum for the teacher to respond to students as learners, but also a learning tool for the students themselves, the teacher should make it clear to students that their individual journal entries will not be graded.
Writing prompts are statements that provide students with a clear, well-defined purpose for a particular writing assignment.9 A teacher needs to communicate clearly to students exactly what he or she expects in a response, such as whether it should include certain components or be a particular length.
Sample writing prompts
(grades 3-5)
After reading The Greedy Triangle by Marilyn Burns,10 give students the following prompts:
• If I could be a shape, I would be a __________ because __________.
• My favorite shape is __________ because __________.
• Why was the triangle greedy?
• Pick one of the shapes in the story and use your own words to describe it.
• Write a letter to a classmate telling him/her how the greedy triangle changed shapes.
• Teacher-Designed Written Tests
Teacher-designed written tests not only help determine a student's grades, but can also inform and guide a teacher's instruction. They do not provide a complete assessment of students' knowledge, but only one piece of the puzzle.
Students need to know what they are being assessed on as well as how they are being assessed. Teacher-made tests should be thoughtful and well-constructed and should include items at different levels on Bloom's taxonomy, such as knowledge and skill problems, selected-response problems, and constructed-response (or "open-ended") problems, which can be either brief or extended. It is helpful for a teacher to construct the test before teaching a unit in order to help clarify in his or her own mind what are the most important elements.
• Achievement Tests
Nearly all teachers must administer standardized or state-wide tests at one time or another. While it is not always possible to receive the results in a timely enough fashion to make adjustments within the same school year, a teacher should look at incoming students' achievement test scores from previous years in order to identify strengths and/or weaknesses. By analyzing test results, a teacher can diagnose strengths and weaknesses of particular students and plan his or her teaching accordingly. An analysis of all test results for a particular grade can illuminate weaknesses in the curriculum that a teacher needs to address or areas that require greater emphasis. Teachers should make use of data from these assessments to help refine content as well as instructional strategies.
Criterion-referenced assessment is a test that measures student achievement against well-defined criteria for a specific learning objective or performance standard. An example of criterion-referenced assessment is the Pennsylvania System of School Assessment (PSSA).
Norm-referenced assessment is a test that measures a student's quantitative scores (such as how many items the student answered correctly) against a normal distribution of scores by other students of the same age or grade. This kind of testing is often used to rank students, measure their relative standing, and assess their general knowledge across broad areas. Examples of norm-referenced assessment are Terra Nova, the Iowa Test of Basic Skills, and SAT-9.
(http://images.rbs.org/assessment/achievement_tests.shtml)

MEDIA PEMBELAJARAN
Media Pembelajaran
Media berasal dari bahasa latin merupakan bentuk jamak dari “Medium” yang secara harfiah berarti “Perantara” atau “Pengantar” yaitu perantara atau pengantar sumber pesan dengan penerima pesan. Beberapa ahli memberikan definisi tentang media pembelajaran. Schramm (1977) mengemukakan bahwa media pembelajaran adalah teknologi pembawa pesan yang dapat dimanfaatkan untuk keperluan pembelajaran. Sementara itu, Briggs (1977) berpendapat bahwa media pembelajaran adalah sarana fisik untuk menyampaikan isi/materi pembelajaran seperti : buku, film, video dan sebagainya. Sedangkan, National Education Associaton (1969) mengungkapkan bahwa media pembelajaran adalah sarana komunikasi dalam bentuk cetak maupun pandang-dengar, termasuk teknologi perangkat keras. Dari ketiga pendapat di atas disimpulkan bahwa media pembelajaran adalah segala sesuatu yang dapat menyalurkan pesan, dapat merangsang fikiran, perasaan, dan kemauan peserta didik sehingga dapat mendorong terciptanya proses belajar pada diri peserta didik.
Brown (1973) mengungkapkan bahwa media pembelajaran yang digunakan dalam kegiatan pembelajaran dapat mempengaruhi terhadap efektivitas pembelajaran. Pada mulanya, media pembelajaran hanya berfungsi sebagai alat bantu guru untuk mengajar yang digunakan adalah alat bantu visual. Sekitar pertengahan abad Ke –20 usaha pemanfaatan visual dilengkapi dengan digunakannya alat audio, sehingga lahirlah alat bantu audio-visual. Sejalan dengan perkembangan ilmu pengetahuan dan teknologi (IPTEK), khususnya dalam bidang pendidikan, saat ini penggunaan alat bantu atau media pembelajaran menjadi semakin luas dan interaktif, seperti adanya komputer dan internet.
Media memiliki beberapa fungsi, diantaranya :
1. Media pembelajaran dapat mengatasi keterbatasan pengalaman yang dimiliki oleh para peserta didik. Pengalaman tiap peserta didik berbeda-beda, tergantung dari faktor-faktor yang menentukan kekayaan pengalaman anak, seperti ketersediaan buku, kesempatan melancong, dan sebagainya. Media pembelajaran dapat mengatasi perbedaan tersebut. Jika peserta didik tidak mungkin dibawa ke obyek langsung yang dipelajari, maka obyeknyalah yang dibawa ke peserta didik. Obyek dimaksud bisa dalam bentuk nyata, miniatur, model, maupun bentuk gambar – gambar yang dapat disajikan secara audio visual dan audial.
2. Media pembelajaran dapat melampaui batasan ruang kelas. Banyak hal yang tidak mungkin dialami secara langsung di dalam kelas oleh para peserta didik tentang suatu obyek, yang disebabkan, karena : (a) obyek terlalu besar; (b) obyek terlalu kecil; (c) obyek yang bergerak terlalu lambat; (d) obyek yang bergerak terlalu cepat; (e) obyek yang terlalu kompleks; (f) obyek yang bunyinya terlalu halus; (f) obyek mengandung berbahaya dan resiko tinggi. Melalui penggunaan media yang tepat, maka semua obyek itu dapat disajikan kepada peserta didik.
3. Media pembelajaran memungkinkan adanya interaksi langsung antara peserta didik dengan lingkungannya.
4. Media menghasilkan keseragaman pengamatan
5. Media dapat menanamkan konsep dasar yang benar, konkrit, dan realistis.
6. Media membangkitkan keinginan dan minat baru.
7. Media membangkitkan motivasi dan merangsang anak untuk belajar.
8. Media memberikan pengalaman yang integral/menyeluruh dari yang konkrit sampai dengan abstrak
Terdapat berbagai jenis media belajar, diantaranya:
1. Media Visual : grafik, diagram, chart, bagan, poster, kartun, komik
2. Media Audial : radio, tape recorder, laboratorium bahasa, dan sejenisnya
3. Projected still media : slide; over head projektor (OHP), in focus dan sejenisnya
4. Projected motion media : film, televisi, video (VCD, DVD, VTR), komputer dan sejenisnya.
Sejalan dengan perkembangan IPTEK penggunaan media, baik yang bersifat visual, audial, projected still media maupun projected motion media bisa dilakukan secara bersama dan serempak melalui satu alat saja yang disebut Multi Media. Contoh : dewasa ini penggunaan komputer tidak hanya bersifat projected motion media, namun dapat meramu semua jenis media yang bersifat interaktif.
Allen mengemukakan tentang hubungan antara media dengan tujuan pembelajaran, sebagaimana terlihat dalam tabel di bawah ini :
Jenis Media 1 2 3 4 5 6
Gambar Diam S T S S R R
Gambar Hidup S T T T S S
Televisi S S T S R S
Obyek Tiga Dimensi R T R R R R
Rekaman Audio S R R S R S
Programmed Instruction S S S T R S
Demonstrasi R S R T S S
Buku teks tercetak S R S S R S
Keterangan :
R = Rendah S = Sedang T= Tinggi
1 = Belajar Informasi faktual
2 = Belajar pengenalan visual
3 = Belajar prinsip, konsep dan aturan
4 = Prosedur belajar
5= Penyampaian keterampilan persepsi motorik
6 = Mengembangkan sikap, opini dan motivasi
Kriteria yang paling utama dalam pemilihan media bahwa media harus disesuaikan dengan tujuan pembelajaran atau kompetensi yang ingin dicapai. Contoh : bila tujuan atau kompetensi peserta didik bersifat menghafalkan kata-kata tentunya media audio yang tepat untuk digunakan. Jika tujuan atau kompetensi yang dicapai bersifat memahami isi bacaan maka media cetak yang lebih tepat digunakan. Kalau tujuan pembelajaran bersifat motorik (gerak dan aktivitas), maka media film dan video bisa digunakan. Di samping itu, terdapat kriteria lainnya yang bersifat melengkapi (komplementer), seperti: biaya, ketepatgunaan; keadaan peserta didik; ketersediaan; dan mutu teknis.
Untuk memahami lebih lanjut tentang Media Pembelajaran, silahkan klik tautan di bawah ini ! Jangan lupa, komentar Anda sangat diharapkan.
(http://akhmadsudrajat.wordpress.com/2008/01/12/media-pembelajaran/)

Gagne dalam Sadiman et al (2008) menyatakan bahwa media pembelajaran adalah berbagai jenis komponen dalam lingkungan siswa yang dapat merangsangnya dalam belajar. Jadi segala sesuatu yang dapat menyalurkan pesan dari pengirim ke penerima sehingga dapat merangsang pikiran, perasaan, perhatian, dan minat siswa sehingga terjadi suatu proses pembelajaran dapat dikategorikan sebagai media pembelajaran.
Pengalaman belajar akan menghasilkan konsep pemahaman yang berbeda-beda tergantung dari proses mendapatkan pengalaman tersebut. Edgar Dale mengklasifikasikan pengalaman belajar dari tingkatan kongkrit ke tingkat abstrak. Tingkatan ini menggambarkan bentuk media yang digunakan dengan hasil pengalaman belajar yang didapat. Klasifikasi ini dinamakan dengan kerucut pengalaman (cone of experience), yang masih dipahami sampai sekarang dalam penentuan media yang sesuai dengan tingkat pengalaman belajar.
Pada bagan kerucut pengalaman terlihat bahwa kondisi media pembelajaran yang membentuk konsep pengalaman belajar yang cenderung kongkrit adalah dibagian dasar dari kerucut yaitu pengalaman langsung, observasi, partisipasi, demonstrasi dan wisata. Kondisi pembelajaran tersebut hanya dapat dilakukan di lingkungan luar kelas atau di ruang terbuka.
Beberapa kegunaan dari media pembelajaran menurut Sadiman et al (2008) adalah :
1. Memperjelas pesan agar tidak terlalu verbalistis.
2. Mengatasi keterbasan ruang, waktu dan daya indera.
3. Mengatasi sifat pasif pada siswa
4. Memberikan persepsi dan pengalaman yang sama pada siswa, dengan latar belakang lingkungan dan kecepatan penyerapan konsep yang beraneka ragam
Sedangkan Rahadi (2008) menuliskan beberapa keuntungan dari media pembelajaran berupa lingkungan sekitar (ruang terbuka), yaitu :
1. Menghemat biaya, karena memanfaatkan benda-benda yang telah ada di ingkungan.
2. Praktis dan mudah dilakukan, tidak memerlukan peralatan khusus seperti listrik.
3. Memberikan pengalaman yang riil kepada siswa, pelajaran menjadi lebih konkrit, tidak verbalistik.
4. Karena benda-benda tersebut berasal dari lingkungan siswa, maka benda-benda tersebut akan sesuai dengan karakteristik dan kebutuhan siswa. Hal ini juga sesuai dengan konsep pembelajaran kontekstual.
5. Pelajaran lebih aplikatif, maksudnya materi belajar yang diperoleh siswa melalui media lingkungan kemungkinan besar akan dapat diaplikasikan langsung, karena siswa akan sering menemui benda-benda atau peristiwa serupa dalam kehidupannya sehari-hari.
6. Media lingkungan memberikan pengalaman langsung kepada siswa. Dengan media lingkungan, siswa dapat berinteraksi secara langsung dengan benda, lokasi atau peristiwa sesungguhnya secara alamiah.
7. Lebih komunikatif, sebab benda dan peristiwa yang ada di lingkungan siswa biasanya mudah dicerna oleh siswa, dibandingkan dengan media yang dikemas (didesain).
Media-media yang terdapat di lingkungan sekitar, ada yang berupa benda-benda atau peristiwa yang langsung dapat dipergunakan sebagai sumber belajar. Selain itu, ada pula benda-benda tertentu yang harus dibuat terlebih dulu sebelum dapat dipergunakan dalam pembelajaran. Media yang dibuat itu biasanya berupa alat peraga sederhana dengan menggunakan bahan-bahan yang terdapat di lingkungan sekitar. Media pembelajaran di sekolah digunakan dengan tujuan antara lain sebagai berikut:
1. Memberikan kemudahan kepada peserta didik untuk lebih memahami konsep, prinsip, dan ketrampilan tertentu dengan menggunakan media yang paling tepat menurut sifat bahan ajar.
2. Memberikan pengalaman belajar yang berbeda dan bervariasi sehingga lebih merangsang minat dan motivasi peserta didik untuk belajar.
3. Menumbuhkan sikap dan ketrampilan tertentu dalam teknologi karena peserta didik tertarik untuk menggunakan atau mengoperasikan media tertentu.
4. Menciptakan situasi belajar yang tidak dapat dilupakan peserta didik.
5. Memperjelas informasi atau pesan pembelajaran.
6. Meningkatkan kualitas belajar mengajar.
Beberapa prinsip pembuatan media pembelajaran yang perlu diperhatikan (Rahadi : 2008), adalah yaitu :
1. Media yang dibuat harus sesuai dengan tujuan dan fungsi penggunaannya.
2. Dapat membantu memberikan pemahaman terhadap suatu konsep tertentu, terutama konsep yang abstrak.
3. Dapat mendorong kreatifitas siswa, memberikan kesempatan kepada siswa untuk bereksperimen dan bereksplorasi (menemukan sendiri)
4. Media yang dibuat harus mempertimbangkan faktor keamanan, tidak mengandung unsur yang membahayakan siswa.
5. Dapat digunakan secara individual, kelompok dan klasikal
6. Usahakan memenuhi unsur kebenaran substansial dan kemenarikan
7. Media belajar hendaknya mudah dipergunakan baik oleh guru maupun siswa
8. Bahan-bahan yang diperlukan untuk membuat hendaknya dipilih agar mudah diperoleh di lingkungan sekitar dengan biaya yang relatif murah
9. Jenis media yang dibuat harus disesuaikan dengan tingkat perkembangan sasaran didik
Dari uraian tersebut maka dapat disimpulkan beberapa kriteria dalam meilih media pembelajaran, yaitu :
1. Kesesuaian, yaitu antara fungsi media dengan tujuan pembelajaran atau kompetensi yang ingin dicapai.
2. Mewakili, yaitu media dapat mewakili konsep yang abstrak.
3. Ekonomis dan praktis, yaitu media tidak memerlukan biaya yang mahal serta mudah dalam penggunaan.
4. Keamanan, yaitu tidak mengakibatkan kecelakaan, atau hal-hal yang dapat mencederai siswa.
5. Keindahan, yaitu media berbentuk menarik dan bernilai estetika
(http://simpangmahar.blogspot.com/2010/02/media-pembelajaran.html)

PENCEMARAN LINGKUNGAN

PENCEMARAN LINGKUNGAN

Polusi atau pencemaran lingkungan adalah masuknya atau dimasukkannya
makluk hidup, zat energi, dan atau komponen lain ke dalam lngkungan atau
berubahnya tatanan lingkungan oleh kegiatan manusia atau oleh proses alam
sehingga kualitas lingkungan turun sampai ke tingkat tertentu yang menyebabkan
lingkungan menjadi kurang atau tidak dapat berfingsi lagi sesuai dengan
peruntukannya (UU Pokok Pengelolaan Lingkungan Hidup No. 4 Tahun 1982).
Pencemaran dapat timbul sebagai akibat kegiatan manusia ataupun
disebabkan oleh alam (misal gunung meletus, gas beracun). Ilmu lingkungan
biasanya membahas pencemaran yang disebabkan oleh aktivitas manusia, yang
dapat dicegah dan dikendalikan.
Karena kegiatan manusia, pencermaran lingkungan pasti terjadi.
Pencemaran lingkungan tersebut tidak dapat dihindari. Yang dapat dilakukan
adalah mengurangi pencemaran, mengendalikan pencemaran, dan meningkatkan
kesadaran dan kepedulian masyarakat terhadap lingkungannya agar tidak
mencemari lingkngan.
Zat atau bahan yang dapat mengakibatkan pencemaran di sebut polutan.
Syarat-syarat suatu zat disebut polutan bila keberadaannya dapat menyebabkan
kerugian terhadap makluk hidup. Contohnya, karbon dioksida dengan kadar
0,033% di udara berfaedah bagi tumbuhan, tetapi bila lebih tinggi dari 0,033%
dapat memberikan efek merusak.
Suatu zat dapat disebut polutan apabila :
1. Jumlahnya melebihi jumlah normal.
2. Berada pada waktu yang tidak tepat.
3. Berada di tempat yang tidak tepat.
Sifat polutan adalah :
1. Merusak untuk sementara, tetapi bila telah bereaksi dengan zat lingkungan
tidak merusak lagi.
2. Merusak dalam waktu lama.
Contohnya Pb tidak merusak bila konsentrasinya rendah. Akan tetapi dalam
jangka waktu yang lama, Pb dapat terakumulasi dalam tubuh sampai tingkat
yang merusak.
A. Macam-macam Pencemaran Lingkungan
1. Berdasarkan Tempat Terjadinya
Menurut tempat terjadinya, pencemaran dibedakan menjadi pencemaran
udara, air, dan tanah.
a. Pencemaran Udara
Pencemaran udara disebabkan oleh asap buangan, misalnya gas CO2
hasil pembakaran, SO, SO2, CFC, CO, dan asap rokok.
1. CO2
Pencemaran udara yang paling menonjol adalah semakin
meningkatnya kadar CO2 di udara. Karbon dioksida itu berasal dari
pabrik, mesin-mesin yang menggunakan bahan bakar fosil
(batubara, minyak bumi), juga dari mobil, kapal, pesawat terbang,
dan pembakaran kayu. Meningkatnya kadar CO2 di udara tidak
segera diubah menjadi oksigen oleh tumbuhan karena banyak hutan
di seluruh dunia yang ditebang. Sebagaimana diuraikan diatas, hal
demikian dapat mengakibatkan efek rumah kaca.
2. CO
Di lingkungan rumah dapat pula terjadi pencemaran.
Misalnya, menghidupkan mesin mobil di dalam garasi tertutup. Jika
proses pembakaran di mesin tidak sempurna, maka proses
pembakaran itu menghasilkan gas CO (karbon monoksida) yang
keluar memenuhi ruangan. Hal ini dapat membahayakan orang yang
ada di garasi tersebut. Selain itu, menghidupkan AC ketika tidur di
dalam mobil dalam keadaan tertutup juga berbahaya. Bocoran gas
CO dari knalpot akan masuk ke dalam mobil, sehingga dapat
menyebabkan kamatian.
3. CFC
Pencemara dara yang berbahaya lainnya adalah gas khloro
fluoro karbon (disingkat CFC). Gas CFC digunakan sebagai gas
pengembang, karena tidak beraksi, tidak berbau, tidak berasa, dan
tidak berbahaya. Gas ini dapat digunakan misalnya untuk
mengembangkan busa (busa kursi), untuk AC (freon), pendingin
pada almari es, dan penyemprot rambut (hair spray).
Gas CFC yang membumbung tinggi dapat mencapai
stratosfer terdapat lapisan gas ozon (O3). Lapisan ozon ini
merupakan pelindung bumi dari pengaruh cahaya ultraviolet. Kalau
tidakl ada lapisan ozon, radiasi cahaya ultraviolet mencapai
permukaan bumi, menyebabkan kematian organisme, tumbuhan
menjadi kerdil, menimbulkan mutasi genetik, menyebebkan kanker
kulit atau kanker retina mata. Jika gas CFC mencapai ozon, akan
terjadi reaksi antara CFC dan ozon, sehingga lapisan ozon tersebut
“berlubang” yang disebut sebagai “lubang” ozon.
Menurut pengamatan melalui pesawat luar angkasa, lubang
ozon di kutub Selatan semakin lebar. Saat ini luasnya telah melebihi
tiga kali luas benua Eropa. Karena itu penggunaan AC harus
dibatasi.
4. SO, SO2
oleh pembakaran fosil (minyak, batubara). Gas tersebut dapat
beraksi dengan gas nitrogen oksida dan air hujan, yang
menyebabkan air hujan menjadi asam. Maka terjadilah hujan asam.
tanah mati. Produksi pertanian merosot. Besi dan logam mudah
berkarat. Bangunan –bangunan kuno, seperti candi, menjadi cepat
aus dan rusak. Demikian pula bangunan gedungdan jembatan.
Gas belerang oksida (SO, SO2) di udara juga dihasilkan
Hujan asam mengakibatkan tumbuhan dan hewan-hewan
5. Asap Rokok
Polutan udara yang lain yang berbahaya bagi kesehatan
adalah asap rokok. Asap rokok mengandung berbagai bahan
pencemar yang dapat menyababkan batuk kronis, kanker patu-paru,
mempengaruhi janin dalam kandungan dan berbagai gangguan
kesehatan lainnya.
Perokok dapat di bedakan menjadi dua yaitu perokok aktif
dan perokok pasif. Perokok aktif adalah mereka yang merokok.
Perokok pasif adalah orang yang tidak merokok tetapi menghirup
asap rokok di suatu ruangan.
Menurut penelitian, perokok pasif memiliki risiko yang
lebih besar di bandingkan perokok aktif. Jadi, merokok di dalam
ruangan bersama orang lain yang tidak merokok dapat mengganggu
kesehatan orang lain.
Akibat yang ditimbulkan oleh pencemaran udara antara lain :
a. Terganggunya kesehatan manusia, seperti batuk dan penyakit
pernapasan (bronkhitis, emfisema, dan kemungkinan kanker paruparu.
b. Rusaknya bangunan karena pelapukan, korosi pada logam, dan
memudarnya warna cat.
c. Terganggunya oertumbuhan tananam, seperti menguningnya daun
atau kerdilnya tanaman akibat konsentrasi SO2 yang tinggi atau gas
yang bersifat asam.
Adanya peristiwa efek rumah kaca (green house effect) yang dapat
menaikkan suhu udara secara global serta dapat mengubah pola
iklim bumi dan mencairkan es di kutub. Bila es meleleh maka
permukaan laut akan naik sehingga mempengaruhi keseimbangan
ekologi.
e. Terjadinya hujan asam yang disebabkan oleh pencemaran oksida
nitrogen.
b. Pencemaran Air
Pencemaran air adalah peristiwa masuknya zat, energi, unsur,
atau komponen lainnya kedalam air sehingga menyebabkan kualitas air
terganggu. Kualitas air yang terganggu ditandai dengan perubahan bau,
rasa, dan warna.
Ditinjau dari asal polutan dan sumber pencemarannya,
pencemaran air dapat dibedakan antara lain :
1. Limbah Pertanian
Limbah pertanian dapat mengandung polutan insektisida atau
pupuk organik. Insektisida dapat mematikan biota sungai. Jika
biota sungai tidak mati kemudian dimakan hewan atau manusia
orang yang memakannya akan keracunan. Untuk mencegahnya,
upayakan agar memilih insektisida yang berspektrum sempit
(khusus membunuh hewan sasaran) serta bersifat biodegradabel
(dapat terurai oleh mikroba) dan melakukan penyemprotan sesuai
dengan aturan. Jangan membuang sisa obet ke sungai. Sedangkan
pupuk organik yang larut dalam air dapat menyuburkan lingkungan
air (eutrofikasi). Karena air kaya nutrisi, ganggang dan tumbuhan
air tumbuh subur (blooming). Hal yang demikian akan mengancam
kelestarian bendungan. bemdungan akan cepat dangkal dan biota
air akan mati karenanya.

2. Limbah Rumah Tangga
Limbah rumah tangga yang cair merupakan sumber pencemaran
air. Dari limbah rumah tangga cair dapat dijumpai berbagai bahan
organik (misal sisa sayur, ikan, nasi, minyak, lemek, air buangan
manusia) yang terbawa air got/parit, kemudian ikut aliran sungai.
Adapula bahan-bahan anorganik seperti plastik, alumunium, dan
botol yang hanyut terbawa arus air. Sampah bertimbun,
menyumbat saluran air, dan mengakibatkan banjir. Bahan
pencemar lain dari limbah rumah tangga adalah pencemar biologis
berupa bibit penyakit, bakteri, dan jamur.
Bahan organik yang larut dalam air akan mengalami penguraian
dan pembusukan. Akibatnya kadar oksigen dalam air turun dratis
sehingga biota air akan mati. Jika pencemaran bahan organik
meningkat, kita dapat menemui cacing Tubifex berwarna
kemerahan bergerombol. Cacing ini merupakan petunjuk biologis
(bioindikator) parahnya pencemaran oleh bahan organik dari
limbah pemukiman.
Dikota-kota, air got berwarna kehitaman dan mengeluarkan bau
yang menyengat. Didalam air got yangdemikian tidak ada
organisme hidup kecuali bakteri dan jamur. Dibandingkan dengan
limbah industri, limbah rumah tangga di daerah perkotaan di
Indonesia mencapai 60% dari seluruh limbah yang ada.
3. Limbah Industri
Adanya sebagian industri yang membuang limbahnya ke air.
Macam polutan yang dihasilkan tergantung pada jenis industri.
Mungkin berupa polutan organik (berbau busuk), polutan
anorganik (berbuaih, berwarna), atau mungkin berupa polutan yang
mengandung asam belerang (berbau busuk), atau berupa suhu (air
menjadi panas). Pemerintah menetapkan tata aturan untuk
mengendalikan pencemara air oleh limbah industri. Misalnya,
limbah industri harus diolah terlebih dahulu sebelum dibuang ke
sungai agar tidak terjadi pencemaran.
Dilaut, sering terjadi kebocoran tangker minyak karena bertabrakan
dengan kapal lain. Minyak yang ada di dalam kapal tumpah
menggenangi lautan dalam jarak ratusan kilometer. Ikan, terumbu
karang, burung laut, dan hewan-hewan laut banyak yang mati
karenanya. Untuk mengatasinya, polutan dibatasi dengan pipa
mengapung agar tidak tersebar, kemudian permukaan polutan
ditaburi dengan zat yang dapat menguraikan minyak.
4. Penangkapan Ikan Menggunakan racun
Sebagia penduduk dan nelayan ada yang menggunakan tuba (racun
dari tumbuhan atau potas (racun)untuk menangkap ikan tangkapan,
melainkan juga semua biota air.
Racun tersebut tidak hanya hewan-hewan dewasa, tetapi juga
hewan-hewan yang masih kecil. Dengan demikian racun yang
disebarkan akan memusnahkan jenis makluk hidup yang ada
didalamnya. Kegiatan penangkapan ikan dengan cara tersebut
mengakibatkan pencemaran di lingkungan perairan dan
menurunkan sumber daya perairan.
Akibat yang dtimbulkan oleh pencemaran air antara lain
a. Terganggunya kehidupan organisme air karena berkurangnya
kandungan oksigen.
b. Terjadinya ledakan populasi ganggang dan tumbuhan air
(eutrofikasi, dan
c. Pendangkalan Dasar perairan.
d. Punahnya biota air, misalnya ikan, yuyu, udang, dan serangga air.
e. Munculnya banjir akibat got tersumbat sampah.
f. Menjalarnya wabah muntaber.
c. Pencemaran tanah
Pencemaran tanah banyak diakibatkan oleh sampah-sampah
rumah tangga, pasar, industri, kegiatan pertanian, dan peternakan.
Sampah dapat dihancurkan oleh jasad-jasad renik menjadi
mineral, gas, dan air, sehingga terbentuklah humus. Sampah organik itu
misalnya dedaunan, jaringan hewan, kertas, dan kulit. Sampah-sampah
tersebut tergolong sampah yang mudah terurai. Sedangkan sampah
anorganik seperti besi, alumunium, kaca, dan bahan sintetik seperti
plastik, sulit atau tidak dapat diuraikan. Bahan pencemar itu akan tetap
utuh hingga 300 tahun yang akan datang. Bungkus plastik yang kita
buang ke lingkungan akan tetap ada dan mungkin akan ditemukan oleh
anak cucu kita setelah ratusan tahun kemudian.
Sebaiknya, sampah yang akan dibuang dipisahkan menjadi dua
wadah. Pertama adalah sampah yang terurai, dan dapat dibuang ke
tempat pembuangan sampah atau dapat dijadikan kompos. Jika
pembuatan kompos dipadukan dengan pemeliharaan cacing tanah, maka
akan dapat diperoleh hasil yang baik. cacing tanah dapat dijual untuk
pakan ternak, sedangkan tanah kompos dapat dijual untuk pupuk. Lihat
gambar 8.19. Proses ini merupakan proses pendaurulangan (recycle).
Kedua adalah sampah yang tak terurai, dapat dimanfaatkan ulang
(penggunaulangan = reuse). Misalnya, kaleng bekas kue digunakan lagi
untuk wadah makanan, botol selai bekas digunakan untuk tempat bumbu
dan botol bekas sirup digunakan untuk menyimpan air minum.
Baik pendaurulangan maupun penggunaulangan dapat
mencegah terjadinya pencemaran lingkungan. Keuntungannya, beban
lingkungan menjadi berkurang. Kita tahu bahwa pencemaran tidak
mungkin dihilangkan. Yang dapat kita lakukan adalah mencegah
dampak negatifnya atau mengendalikannya.
Selain penggunaulangan dan pendaurulangan, masih ada lagi
upaya untuk mencegah pencemaran, yaitu melakukan pengurangan
bahan/ penghematan (reduce), dan melakukan pemeliharaan (repair). Di
negara maju, slogan-slogan reuse, reduce, dan repair, banyak diedarkan
ke masyarakat.
Akibat yang ditimbulkan oleh pencemaran tanah antara lain
a. Terganggunya kehidupan organisme (terutama mikroorganisme
dalam tanah).
b. Berubahnya sifat kimia atau sifat fisika tanah sehingga tidak baik
untuk pertumbuhan tanaman, dan
c. Mengubah dan mempengaruhi keseimbangan ekologi.
2. Berdasarkan Macam Bahan Pencemaran
Menurut macam bahan pencemarnya, pencemaran dibedakan menjdi
berikut ini,
a. Pencemaran kimiawi : CO2 logam berat (Hg, Pb, As, Cd, Cr, Ni,)
bahan raioaktif, pestisida, detergen, minyak, pupuk anorganik.
b. Pencemaran Biolagi : mikroorganisme seperti Escherichia coli,
Entamoeba coli, Salmonella thyposa.
c. Pencemara fisik : logam, kaleng, botol, kaca, plastik, karet.
d. Pencemaran Suara : kebisingan.
Pencemaran Suara (kebisingan)
Dikota-kota atau di daerah dekat industri / pabrik sering
terjadi kebisingan. Pencemaran suara disebabkan oleh masuknya bunyi
gaduh diatas 50 desibel (disingkat dB, merupakan ukuran tingkat
kebisingan). Bunyi tersebut mengganggu kesehatan dan ketenangan
manusia. Kebisingan menyebabkan penduduk menjadi sulit tidu,
bahkan dapat mengakibatkan tuli, gangguan kejiwaan, dan dapat pula
menimbulkan penyakit jantung, gangguan janin dalam kandungan, dan
stress.
Saat ini telah diusahakan agar mesin-mesin yang digunakan
manusia tidak terlalu bising. jika bising harus diusahakan adanya
isolator. menanam tanaman berdaun rimbun di halaman rumah
meredam kebisingan. Bagi mereka yang suka mendengarkan musik
yang hingar bingar, hendaknya mendengarkan di tempat khusus (misal
di dalam kamar) agar tidak mengganggu orang lain.
3. Berdasarkan Tingkat Pencemaran
Menurut tingkat pencemarannya, pencemaran dibedakan menjadi
sebagai berikut.
a. Pencemaran ringan, yaitu pencemaran yang dimulai menimbulkan
gangguan ekosistem lain. Contohnya pencemaran gas kendaraan
bermotor.
b. Pencemaran kronis, yaitu pencemaran yang mengakibatkan penyakit
kronis. Contohnya pencemaran Minamata, Jepang.
c. Pencemaran akut, yaitu pencemaran yang dapat mematikan seketika.
Contohnya pencemaran gas CO dari knalpot yang mematikan orang di
dalam mobil tertutup, dan pencemaran radioaktif.
B. Parameter Pencemaran Lingkungan
Untuk mengukur tingkat pencemaran diasuatu tempat digunakan
parameter pencemaran. Parameterpencemaran digunakan sebagai indikator
(petunjuk) terjadinya pencemaran dan tingkat pencemaran yang telah terjadi.
Paarameter pencemaran meliputi parameter fisik, parameter kimia, dan
parameter biologi.
1. Parameter Fisik
Parameter fisik meliputi pengukuran tentang warna, rasa, bau, suhu,
kekeruhan, dan radioaktivitas.
2. Parameter Kimia
Parameter kimia dilakukan untuk mengetahui kadar CO2, pH, keasaman,
kadar logam, dan logam berat. Sebagai contoh berikut disajukan
pengukuran pH air, kadar CO2, dan oksigen terlarut.
a. Pengukuran pH air
Air sungai dalam kondisi alami yang belum tercemar memiliki
rentangan pH 6,5 – 8,5. Karena pencemaran, pH air dapat menjadi
lebih rendah dari 6,5 atau lebih tinggi dari 8,5. Bahan-bahan organik
biasanya menyebabkan kondisi air menjadi lebih asam.
Kapurmenyebabkan kondisi air menjadi alkali (basa). jadi, perubahan
pH air tergantung kepada macam bahan pencemarnya.
Perubahan nilai pH mempunyai arti penting bagi kehidupan air. Nilai
pH yang rendah (sangat asam) atau tinggi (sangat basa) tidak cocok
untuk kehidupan kebanyakan organisme. Untuk setiap perubahan satu
unit skala pH (dari 7 ke 6 atau dari 5 ke 4) dikatakan keasaman naik 10
kali. Jika terjadi sebaliknya, keasaman turun 10 kali. Keasaman air
dapat diukur dengan sederhana yaitu dengan mencelupkan kertas
lakmus ke dalam air untuk melihat perubahan warnanya.
b. Pengukuran Kadar CO2
Gas CO2 juga dapat larut ke dalam air. Kadar gas CO2 terlarut sangat
dipengaruhi oleh suhu, pH, dan banyaknya organismeyang hidup di
dalam air. Semakin banyak organisme di dalam air, semakin tinggi
kadar karbon dioksida terlarut (kecuali jika di dalam air terdapat
tumbuhan air yang berfotosintesis). Kadar gas CO dapat diukur dengan
cara titrimetri.
c. Pengukuran Kadar Oksigen Terlarut
Kadar oksigen terlarut dalam air yang alami berkisar 5 – 7 ppm (part
per million atau satu per sejita; 1ml oksigen yang larut dalam 1 liter air
dikatakan memiliki kadar oksigen 1 ppm). Penurunan kadar oksigen
terlarut dapat disebabkan oleh tiga hal :
1. Proses oksidasi (pembongkaran) bahan-bahan organik.
2. Proses reduksi oleh zat-zat yang dihasilkan baktri anaerob dari
dasar perairan.
3. Proses pernapasan orgaisme yang hidup di dalam air, terutama
pada malam hari.
Pencemaran air (terutama yang disebabkan oleh bahan
pencemar organik) dapat mengurangi persediaan oksigen terlarut. hal ini
akan mengancam kehidupan organisme yang hidup di dalam air. Semakin
tercemar, kadar oksigen terlerut semakin mengecil. Untuk dapat mengukur
kadar oksigen terlarut, dilakukan dengan metode Winkler.
Parameter kimia yang dilakukan melalui kegiatan pernapasan
jasad renik dikenal sebagai parameter biokimia. contohnya adalah
pengukuran BOD dab COD.
Pengukuran BOD
Bahan pencemar organik (daun, bangkai, karbohidrat, protein)
dapat diuraikan oleh bakteri air. Bakteri memerlukan oksigen untuk
mengoksidasikan zat-zat organik tersebut. akibatnya, kadar oksigen
terlarut di air semakin berkurang. Semakin banyak bahan pencemar
organik yang ada di perairan, semakin banyak oksigen yang digunakan,
sehingga mengakibatkan semakin kecil kadar oksigen terlarut.
Banyaknya oksigen terlerut yang diperlukan bakteri untuk
mengoksidasikan bahan organik disebut sebagai Konsumsi Oksigen
Biologis (KOB) atau Biological Oksigen Demand, yang biasa disingkat
BOD. Angka BOD ditetapkan dengan menghitung selisih antara oksigen
terlarut awal dan oksigen terlarut setelah air cuplikan (sampel) disimpan
selama 5 hari pada suhu 20oC. Karenanya BOD ditulis secara lengkap
BOD205 atau BOD5 saja. Oksigen terlarut awal diibaratkan kadar oksigen
maksimal yang dapat larut di dalam air. Biasanya, kadar oksigen dalam air
diperkaya terlebih dahulu dengan oksigen. Setelah disimpan selama 5 hari,
diperkirakan bakteri telah berbiak dan menggunakan oksigen terlarut
untuk oksidasi. Sisa oksigen terlarut yang ada diukur kembali. Akhirnya,
konsumsi oksigen dapat diketahui dengan mengurangi kadar oksigen awal
dengan oksigen akhir (setelah 5 hari).
3. Parameter Biologi
Di alam terdapat hewan-hewan, tumbuhan, dan mikroorganisme
yang peka dan ada pula yang tahan terhadap kondisi lingkungan tertentu.
Organisme yang peka akan mati karena pencemaran dan organisme yang
tahan akan tetap hidup. Siput air dan Planaria merupakan contoh hewan
yang peka pencemaran. Sungai yang mengandung siput air dan planaria
menunjukkan sungai tersebut belum mengalami pencemaran. Sebaliknya,
cacing Tubifex (cacing merah) merupakan cacing yang tahan hidup dan
bahkan berkembang baik di lingkungan yang kaya bahan
organik,meskipun spesies hewan yang lain telah mati. Ini berarti
keberadaab cacing tersebut dapat dijadikan indikator adanya pemcemaran
zat organik. Organisme yang dapat dijadikan petunjuk pencemaran dikenal
sebagai indikator biologis.
Indikator biologis terkadang lebih dapat dipercaya daripada
indikator kimia. Pabrik yang membuang limbah ke sungai dapat mengatur
pembuangan limbahnya ketika akan dikontrol oleh pihak yang berwenang.
Pengukuran secara kimia pada limbah pabrik tersebut selalu menunjukkan
tidak adanya pencemaran. Tetapi tidak demikian dengan makluk hidup
yang menghuni ekosistem air secara terus menerus. Disungai itu terdapat
hewan-hewan, mikroorganisme, bentos, mikroinvertebrata, ganggang,
yang dapat dijadikan indikator biologis.
C. Dampak Pencemaran Lingkungan
1. Punahnya Spesies
Sebagaimana telah diuraikan, polutan berbahaya bagi biota air dan
darat. Berbagai jenis hewan mengelami keracunan, kemudian mati.
Berbagai spesies hewan memiliki kekebalan yang tidak sama. Ada yang
peka, ada pula yang tahan. Hewan muda, larva merupakan hewan yang
peka terhadap bahan pencemar. Ada hewan yang dapat beradaptasi
sehingga kebal terhadap bahan pencemar., adpula yang tidak. Meskipun
hewan beradaptasi, harus diketahui bahwa tingkat adaptasi hewan ada
batasnya. Bila batas tersebut terlampui, hewan tersebut akan mati.
2. Peledakan Hama
Penggunaan insektisida dapat pula mematikan predator. Karena
predator punah, maka serangga hama akan berkembang tanpa kendali.
3. Gangguan Keseimbangan Lingkungan
Punahnya spasies tertentu dapat mengibah pola interaksi di dalam
suatu ekosistem. Rantai makanan, jaring-jaring makanan dan lairan energi
menjadiberubah. Akibatnya, keseimbangan lingkngan terganggu. Daur
materi dan daur biogeokimia menjadi terganggu.
4. Kesuburan Tanah Berkurang
Penggunaan insektisida mematikan fauna tanah. Hal ini dapat
menurunkan kesuburan tanah. Penggunaan pupuk terus menerus dapat
menyebabkan tanah menjadi asam. Hal ini juga dapat menurunkan
kesuburan tanah. Demikian juga dengan terjadinya hujan asam.
5. Keracunan dan Penyakit
Orang yang mengkonsumsi sayur, ikan, dan bahan makanan
tercemar dapat mengalami keracunan. ada yang meninggal dunia, ada yang
mengalami kerusakan hati, ginjal, menderita kanker, kerusakan susunan
saraf, dan bahkan ada yang menyebabkan cacat pada keturunanketurunannya.
6. Pemekatan Hayati
Proses peningkatan kadar bahan pencemar melewati tubuh
makluk dikenal sebagai pemekatan hayati (dalam bahasa Inggrisnya
dikenal sebagai biomagnificition.
7. Terbentuknya Lubang Ozon dan Efek Rumah Kaca
Terbentuknya Lubang ozon dan terjadinya efek rumah kaca
merupakan permasalahan global yang dirasakan oleh semua umat manusia.
Hal ini disebabkan karena bahan pencemar dapat tersebar dan
menimbulkan dampak di tempat lain.
Usaha-usaha Mencegah Pencemaran Lingkungan
1. Meenempatkan daerah industri atau pabrik jauh dari daerah perumahan
atau pemukiman penduduk.
2. Pembuangan limbah industri diatur sehingga tidak mencemari lingkungan
atau ekosistem.
3. Pengawasan terhadap penggunaan jenis-jenis pestisida dan zat kimia lain
yang dapat menimbulkan pencemaran lingkungan.
4. Memperluas gerakan penghijauan.
5. Tindakan tegas terhadap pelaku pencemaran lingkungan.
6. Memberikan kesadaran terhadap masyarakat tentang arti lingkungan hidup
sehingga manusia lebih mencintai lingkungan hidupnya.
DAFTAR PUSTAKA
Pratiwi, D.A 1998. Buku Penuntun Biologi SMU kelas 1. Jakarta, Erlangga.
Retnowati, Pristilla. 1999. Seribu Pena Biologi SMU Jilid I. Jakarta : Erlangga.
Syamsuri, Istamar. 2000. Biologi 2000 SMU jilid B. Jakarta : Erlangga
Surakarta, 2 Juli 1998
Bintoro
bkusumoh@yahoo.com