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Learning science is a process that is both individual and social. Like researchers, engineers, mathematicians, and physicians who work in teams to answer questions and to solve problems, students in science classrooms often need to interact with their peers to develop deeper knowledge of scientific concepts and ideas. The GroupWork activities were developed to foster an environment in which groups of students work cooperatively to

  • plan experiments,
  • collect and review data,
  • ask questions and offer solutions,
  • use data to explain and justify their arguments,
  • discuss ideas and negotiate conflicting interpretations,
  • summarize and present findings,
  • and explore the societal implications of the scientific enterprise.

The GroupWork environment is one in which students are “doing science” as a team. Suggestions about when to introduce these group activities are included in the Teacher Activity Notes.

Format and Organization of GroupWork Activities

Each GroupWork activity includes teacher activity notes, an activity guide, an individual report, resource materials, and at times, data sheets. The activity guide contains instructions for the group's task and questions to be discussed as students plan for and work on a group product. Resource materials are varied. They might include textual information, visual resources such as photos, drawings, graphs or diagrams, video, or audiotapes. Individual reports by students are an integral part of each activity to be completed in class or as part of a homework assignment. Planning information for the teacher is found on the Teacher Activity Notes page.

Sets of GroupWork activities are organized around a central concept or a basic scientific question-a “big idea.” Ideally, as students rotate to complete these activities, they encounter this central idea, question, or concept in different scientific contexts or in different social settings. These rotations provide students with multiple opportunities to grapple with the material, explore related questions and dilemmas, look at different representations, and think of different applications. Figure 1 shows how students rotate from activity to activity around the “big idea.”

The GroupWork activities were designed to be open-ended to foster the development of higher-order thinking skills. Such open-endedness allows students to decide as a group how to go about completing the task, as well as what the final group product might be. Open-ended group activities increase the need for interaction as students serve as resources for one another, draw upon each other's expertise and knowledge, and take advantage of their different problem- solving strategies. When groups are heterogeneous and include students with many different intellectual abilities, the repertoire of strategies and previous experiences is rich and diverse. As students interact with their peers, they learn how to communicate effectively, justify their arguments when challenged, and examine scientific problems from different perspectives. Such interaction scaffolds students' knowledge of scientific concepts and principles.

These GroupWork activities then are quite different from traditional lab activities that include more step-by-step procedures and are crowded with details. In addition to using reading, writing, and computing (the traditional academic abilities), students use many different intellectual abilities to complete their task. They make observations, pose questions, plan investigations; they use and create visual models, access and interpret scientific information from different sources and from different media, and convey scientific findings in diagrams, graphs, charts, or tables. The use of a wide array of resource materials provides students with additional ways to access and use information, as well as with additional opportunities to demonstrate their intellectual competence and be recognized for their contributions. We have included in the Teacher Activity Notes a partial list of some of the multiple abilities students might be observed using in these group activities.

When group activities are open-ended, rich, and intellectually demanding, a Single student will not be able to complete the task in a timely fashion by himself or herself. Making students responsible as a group to interpret a challenging task and to design a common product or group presentation increases group interdependence. Teachers know, however, that it is also important to hold each student personally accountable for contributing to the group's success and for mastering the concepts or the big idea of the activity. To do so, students are required to complete individual written reports in which they respond in their own words to key discussion questions and summarize what they have learned in the group activity. These written responses can be useful for teachers in gauging and monitoring student knowledge and progress.

Role of the Teacher Planning ahead and organizing the classroom for GroupWork is important for the successful implementation of group activities. We suggest that you refer to Elizabeth Cohen's book, Designing GroupWork: Strategies for Heterogeneous Classrooms, published by Teachers College Press in 1994. (See also “Complex Instruction in the Science Classroom: The Human Biology Curriculum in Action” by R. A. Lotan, J. A. Bianchini, and N. C. Holthuis in Cooperative Learning in Science: A Handbook for Teachers edited by R. J. Stahl, published by Addison-Wesley Publishing Company.)

Many teachers have realized that when students work in groups, direct instruction is no longer practical. The teacher can't be everywhere at once, telling students exactly what to do and how to do it. Thus, teachers delegate authority to students and students take responsibility for their own behavior and their own learning. Rather than constantly turning to the teacher for help, students talk with each other to find out what they should be doing and to solve the challenging problems assigned to them. Teaching students to work collaboratively and to be responsible to one another as a group is an important prerequisite for successful GroupWork. Students also support the smooth operation of groups when they have learned to play different roles in their groups effectively. For example, the facilitator sees to it that everyone in the group knows what has to be done and gets help when necessary. The recorder keeps notes of the group's discussions and checks to see if individual reports have been completed. The materials manager sees to it that the group has all the equipment necessary and that the tables are cleared at the end of the lesson. The reporter presents the findings of the group during wrap-up time. When the activity involves hazardous materials, a safety officer might be needed. Every student must have a role to play, and roles rotate so students learn how to perform each role competently.

Delegating authority doesn't mean that the teacher withdraws from the class or completely stays out of the action. Instead of being the focal point of the classroom, the teacher carefully observes the students as they work in the groups, stimulates and extends their thinking, and provides specific feedback.

Equalizing Participation among Members of the Group Making sure that all members of the group have access to the materials and that one group member doesn't take over or dominate the group while another withdraws are among the principal challenges of GroupWork. Teachers can increase participation of students by explaining how the different intellectual abilities are relevant to the successful completion of the task. The teacher states that while no one group member has all the abilities, everyone in the group has some of the intellectual abilities necessary to complete the task successfully. Furthermore, after careful observation of the students' work in groups, the teacher can publicly acknowledge those students who have made relevant contributions and explain specifically how these contributions made the group move forward and become more successful. It is important that the teacher be able to notice the intellectual contributions of students who have low academic or peer status and who are frequently left out of group interactions. These strategies are particularly relevant in untracked classrooms, where students have a wide range of previous academic achievement (mainly in reading) or where significant proportions of students are English-language learners. Teachers, classmates, and the low-status students themselves need to understand that when many different intellectual abilities are necessary to complete a task successfully, everybody's contribution becomes critical to the success of the group. As more previously low-achieving students feel and are expected to be competent, their participation in the group increases, and subsequently their learning achievements increase as well.

Rachel A. Lotan, Ph.D.

School of Education

Stanford University

Figure 1 Activity Rotation in GroupWork

GroupWork Contents

Activity Duration Materials Activity Summary
1. Orientation Activity: Is Seeing Believing? 30 minutes TV, VCR, and videotape As a class, students watch two video clips and record their observations. In groups, they explore similarities and differences in observations. They then write a scenario on the interaction of personal differences and perception.
2. What Is It Like to Be Blind? 40 minutes Blindfold; a large box with common to unusual objects; and brochures, articles, or information packets about services for and special needs of blind In this activity, students learn what it is like to be blind. They attempt to identify objects blind folded and create a plan to help a student adjust to life in their the blind classroom.
3. Cushioning the Blow 40 minutes Egg without shell and art supplies (cardboard, scissors, tape, cloth, cotton, string, wood, rubber, plastic tubing, and/or packing material) Students explore how the eye is protected and how these different protective layers function. They then construct and test a structure to protect a shell-less egg. The compare their egg's protection to that of the eye.
4. The Way Lenses Work 50 minutes Several converging and diverging lenses and a common object Students learn how converging and diverging lenses help solve the problems of nearsightedness and farsightedness. They create a presentation for third graders on the benefits of glasses.
5. The Versatile Eye 40 minutes Colored, white, and black squares of paper; dark sunglasses; a black felt pen; poster and art supplies In this activity, students conducts an experiment to explore the relationship between the structure paper; and function of the retina. They then create a model of the retina to explain their findings to the class.
6. Culminating Activity: Looking into the Future: The Bionic Eye 40 minutes Art supplies In this activity, students study the eye as part of the visual system. They design a bionic eye and attempt to sell their design to company.

Groupwork 1: Teacher Activity Notes - Is Seeing Believing?

Big Idea: What Makes the Visual System a System?

PLAN

Summary As a class, students watch three video clips and record their observations. In groups, they explore similarities and differences in observations. They then write a scenario on the interaction of personal differences and perception.

Group Size 4 to 5 students

Objectives

Students:

  • clearly describe what they have observed.
  • compare and contrast what they have observed with their classmates.
  • identify the type of things that influence what a person sees.

Student Materials

TV, VCR, and videotape. (Any selected videotape will work. Nature videos with the sound turned off work well.)

Multiple Abilities

  • Reasoning ability (making connections between ideas/concepts, applying previous knowledge, examining an issue from various perspectives)
  • Communication skills (explaining clearly and fully, using words precisely)
  • Creativity (generating alternatives, imagining what it would be like to be someone else)

Estimated Time 30 minutes

Suggested Use

  • This set of activities works well near the end of the unit.

IMPLEMENT

  • Each student should use her or his journal to record her or his observations; each group, a team chart.
  • Show two action scenes, each one to two minutes long, to the entire class.
  • Do not introduce the clips. The scenes should not include sound. Ask students to refrain from writing while the video clips play. Pause after each to give students time to record in detail what they saw.
  • After watching the video clips, break the class into groups. Have each group construct one chart. The chart should display similarities and differences in observations. In their discussions, have students consider the following questions: Who has seen the clips (the commercials or movies) before? Did that make a difference in what they saw compared to others? Did students know the actors? Did that influence what they wrote down? Did some find one clip interesting and another boring? Did that have an impact?

Conclude GroupWork Activity 1 by asking the following questions:

  • If sound had been included in the video clips, would students have remembered things more clearly? How are the auditory and visual systems related?
  • How are seeing and believing related?
  • In this society, what influences people's ability to see and believe? (Examples include culture, education, interests, and emotional state.) What are possible outcomes of such differences?

(Examples include discrimination, violence, and social change.)

ASSESS

Use the journal entries, individual report, group chart, group discussion, and group product to assess if students can

  • clearly describe what they have observed.
  • explain how different people perceive different things.
  • describe how mood, interests, and physical location influence what a person sees.

Extend GroupWork Activity 1 by exploring how new ways of seeing a phenomenon are crucial to new theories in science. Examples include Darwin's evolution, Mendel's genetics, Einstein's theory of relativity, and Watson and Crick's double helix.

GroupWork 1: Activity Guide - Is Seeing Believing? (Student Reproducible)

Big Idea: What Makes the Visual System a System?

Is seeing believing? Your friend insists she saw you walking home from school yesterday. After all, she saw a person with the same color hair, wearing the same clothes, and carrying the same backpack as yourself. You, however, know your friend could not have seen you-you took the bus home. Why the mistake?

Materials

  • TV, VCR, and videotape

Procedure

1. Watch the video clips. After each clip, pause the VCR and write down what you saw in your journal. Do not discuss the clips while you write.

2. Compare your descriptions of each clip. Create a group chart of similarities and differences.

3. Discuss the following questions: Did group members see the same things in each clip? Why or why not?

4. Create a story in which two observers see and react to the same event. The observers should differ in interests, age, gender, ethnicity, and/or physical location. In your story, explain the following:

  • What did each observer see?
  • How did what each observer see affect his or her feelings about the event? Conclusions about what occurred? What he or she did?
  • How does your story relate to the title of this activity: Is Seeing Believing?

GroupWork 1: Individual Report - Is Seeing Believing? (Student Reproducible)

Big Idea: What Makes the Visual System a System?

1. Did you and other group members see the same things in the video clips? Why or why not?

2. For each observer in your group's story, describe what he or she saw and why.

3. Is seeing always believing? Explain.

GroupWork 2: Teacher Activity Notes - What Is It Like to Be Blind?

Big Idea: What Makes the Visual System a System?

PLAN

Summary In this activity, students learn what it is like to be blind. They attempt to identify objects blindfolded and create a plan to help a blind student adjust to life in their classroom.

Group Size 4 to 5 students

Objectives

Students:

  • identify sensory systems used to guess objects.
  • explain how the other systems of the body interact with the visual system.
  • describe services for and special needs of the blind.

Student Materials

Blindfold; a large box with common to unusual objects; and brochures, articles, or information packets about services for and special needs of the blind

Multiple Abilities

  • Reasoning ability (making connections between ideas/concepts, logically analyzing a problem)
  • Ability to make plans (organizing group, focusing on goal, prioritizing tasks and ideas)
  • Creativity (generating alternatives, imagining what it would be like to be someone else or experience something you have never experienced)

Estimated Time 40 minutes

Suggested Use

  • This set of activities works well near the end of the unit.

IMPLEMENT

  • Place at least five objects-from the everyday to the unusual-in a box with a lid. Cut a hole in the lid large enough for a hand to reach through but small enough so that the objects inside cannot be seen.

Conclude GroupWork Activity 2 by asking the following questions:

  • What are other disabilities that make it difficult to know and experience the world?
  • How does loss of one's visual system affect other systems within the body?
  • Does anyone know a blind person? How does he or she live? What does he or she do?

ASSESS

Use the group data sheet, presentation, individual report, and group discussion to assess if students can

  • explain the purpose of the visual system (how people use the visual system in their everyday life).
  • explain the interaction between the visual system and the other systems of the body.
  • identify services for and special needs of the blind.

Extend GroupWork Activity 2 by

  • If possible and appropriate, invite a blind person to talk with your class.
  • Asking students to write a short report on one of the following topics.
  1. Louis Braille and the development of Braille.
  2. Diseases that cause blindness and prevention/cures.
  3. Problems blind people encountered or still encounter in society and enacted or possible solutions to these problems.

Groupwork 2: Activity Guide - What Is It Like to Be Blind? (Student Reproducible)

Big Idea: What Makes the Visual System a System?

Imagine that you couldn't see. What would your life be like? How would you get to school in the morning? How would you complete your homework? How would you play with your friends?

Materials

  • Blindfold, a large box with objects, and information about services for and special needs of the blind.

Procedure

1. Take turns trying to identify at least three objects in the box while blindfolded. Record your guesses about the objects. Compare your guesses to what the objects actually are.

2. As a group, discuss the following questions:

  • What senses did you use to guess the objects? Was guessing easy or difficult? Explain.
  • People often use their visual system to identify objects. How else do people use their visual system to get through a typical day?
  • With what other systems in the body does the visual system interact? How do you know?
  • In your opinion, what problems do blind people encounter in our society? How could you find out more about the services for the blind in your community? How could you help people in your community who cannot see?

3. You just learned that a blind student will be joining your class next week. Using the resources available, create a plan to help this student learn about your classroom. Include the following:

  • a description of your classroom.
  • ways to help him or her remember the location of people and things.
  • ways to help him or her participate in group activities.
  • ways to include the Braille alphabet in teaching and learning.

GroupWork 2: Individual Report - What It Is Like to Be Blind? (Student Reproducible)

Big Idea: What Makes the Visual System a System?

1. What senses did you use to guess the objects? Was guessing easy or difficult? Explain.

2. With what other systems in the body does the visual system interact? Provide two examples.

3. What are three suggestions to help a student who is blind adjust to your classroom? For each suggestion, explain why it would be helpful.

GroupWork 3: Teacher Activity Notes - Cushioning the Blow

Big Idea: What Makes the Visual System a System?

PLAN

Summary Students explore how the eye is protected and how these different protective layers function. They then construct and test a structure to protect a shell-less egg. They compare their egg's protection to that of the eye.

Group Size 4 to 5 students

Objectives

Students:

  • identify and describe the function of the parts of the eye that provide protection.
  • explain how the protective layers function.
  • predict how damage to the eye would impact the rest of the visual system.

Student Materials

Egg without shell and building materials (cardboard, scissors, tape, cloth, cotton, string, wood, rubber, plastic tubing, and/or packing material)

Multiple Abilities

  • Artistic/creative ability (thinking of new uses for familiar objects)
  • Reasoning ability (making connections between ideas/concepts, logically analyzing the problem, applying previous knowledge, examining an issue from various perspectives)
  • Spatial/visual ability (drawing an idea, creating a model)
  • Creativity (generating alternatives)

Estimated Time 50 minutes

Suggested Use

  • This set of activities works well near the end of the unit.

IMPLEMENT

  • Three days before beginning this activity place one egg per group in white vinegar to dissolve the shell. (Make a few extra. They break easily!) Wash each shell-less egg gently in water to remove any remaining shell or vinegar.
  • One student Resource includes an extensive description of the protective layers of the eye; two others, detailed drawings of these structures. Rather than including all these Resources, you may choose to discuss this information with your students prior to implementation of this activity.
  • One way students could test their structures' effectiveness is by dropping them from bleachers, stairs, or a second floor.

Conclude Groupwork Activity 3 by asking the following questions:

  • What part does the eye play in the visual system?
  • Why do we sometimes need additional protection for our eyes? What kinds of additional protection do we use?
  • Why is the testing of a design important?
  • The egg's protection models the eye's protection. What are other examples of models in science? How do scientists use models in their work?

ASSESS

Use the individual report, group discussion, and group presentation to assess if students can

  • identify the components that protect the eye.
  • explain how the visual system is a system (what a system is, its purpose, how its parts interact).
  • describe the strengths and limitations of models (the egg's protection as a model of the eye's protection).
  • predict how damage to the eye would impact the rest of the visual system.

Extend GroupWork Activity 3 by

  • using the activity as an introduction to the more general topic of safety-safety in the science lab or on the athletic field.
  • having students investigate if other organisms' eyes are protected in the same way as humans? (Aquatic animals, for example, do not produce tears. They do not need them because their eyes are in constant contact with water.) Examining the eyes of other organisms can spark a discussion of design and the importance of fitting design to function.

GroupWork 3: Activity Guide - Cushioning the Blow (Student Reproducible)

Big Idea: What Makes the Visual System a System?

Your eyes are an important part of the visual system. They also can be easily infected or damaged. In this activity, you explore how your fragile eyes are kept safe and healthy.

Materials

  • Egg without shell and building materials

Procedure

1. Examine the Resource. Discuss

  • How is the eye protected? How does each form of protection help keep the eye healthy?
  • How do these various protective layers function?
  • How would damage to the eye affect the rest of the visual system?

2. Imagine the shell-less egg is an eye. Design and build a structure to protect it.

3. Present your structure to the class. In your presentation, explain the following:

  • Why did you design and build your structure as you did?
  • How is your egg's protection similar to and different from the eye's protection?
  • How could you improve your design?

Test the effectiveness of your structure with your audience.

GroupWork 3: Resource 1 - Cushioning the Blow (Student Reproducible)

Big Idea: What Makes the Visual System a System?

GroupWork 3: Resource 2 - Cushioning the Blow (Student Reproducible)

Big Idea: What Makes the Visual System a System?

Groupwork 3: Resource 3 - Cushioning the Blow (Student Reproducible)

Big Idea: What Makes the Visual System a System?

Eyebrows, Eyelashes, and Eyelids

Eyebrows protect the eye by preventing dust, sweat, and glare from entering.

Eyelashes also prevent small particles in the air from entering the eye. Oil from small glands coat the eyelashes so they do not become dry and brittle. When one of these oil glands becomes infected, a sty develops.

The upper and lower eyelids protect the eye by blinking. Blinking is a reflex action. One blink takes about 0.1 seconds. Blinking cleans the eye and keeps it moist. Blinking also protects the eye from approaching objects that might cause damage.

Bone

Two-thirds of our eye (the part hidden from view) is protected by a bony cavity. Moreover, each cavity is lined with a layer of fatty tissue. The fat cushions and absorbs most of the shock from blows to the eye. The one-third of our eye that sticks out of these bony, padded cavities needs the protection of the lids and lashes.

Extrinsic Eye Muscles

What prevents our eyeballs from falling out of their sockets when we bend over? (A sick thought!) How about muscles? There are six muscles attached to the white part of each eyeball. They help protect the eye by anchoring it to its cavity.

The Conjunctiva

There is a thin, clear membrane that lines the inner eyelid and folds over to protect the front of the eyeball. This membrane is called the conjunctiva. Irritation of this membrane is known as conjunctivitis or “pink eye.” “Pink eye” may be caused by allergies, smoke, Wind, air pollutants, chlorine in swimming pools, or lack of sleep. Some forms are caused by bacteria or viruses. These forms can be passed from person to person. Antibiotics can be used to treat “pink eye” caused by bacteria.

Tears

Tears, believe it or not, are produced in small quantities all the time-not just when you Cry. Glands, located on top of the eye, produce tears. The tears flow across the surface of the eyes-helped by blinking. Tears help protect the eye in three ways. One, they help keep the eye clean. They contain an enzyme that kills bacteria. Two, they help lubricate the eyelids and eye so that the eye's surface is not scratched. Three, tears prevent the eye's exposed cells (the eye is composed of living cells) from drying out and dying.

GroupWork 3: Individual Report - Cushioning the Blow (Student Reproducible)

Big Idea: What Makes the Visual System a System?

1. What are three forms of protection around the eye? How does each help keep the eye healthy?

2. Briefly describe how you protected your egg. Explain how your egg's protection is similar to and different from the eye's protection.

3. How do the protective structures of the eye function?

Groupwork 4: Teacher Activity Notes - The Way Lenses Work

Big Idea: What Makes the Visual System a System?

PLAN

Summary Students learn how converging and diverging lenses help solve the problems of nearsightedness and farsightedness. They create a presentation for third graders on the benefits of glasses.

Group Size 4 to 5 students

Objectives

Students:

  • compare and contrast the shape of converging and diverging lenses.
  • compare and contrast the problems of farsightedness and nearsightedness.
  • explain how corrective lenses interact with the lens of the eye.

Student Materials

Several converging and diverging lenses and a common object

Multiple Abilities

  • Reasoning ability (making connections between ideas/concepts, logically analyzing the problem)
  • Spatial/visual ability (drawing an idea, creating a model)
  • Ability to make plans (organizing the group, breaking a task into its parts)
  • Communication skills (explaining clearly and fully, using words precisely)
  • Creativity (imaging what it would be like to be someone else)

Estimated Time 40 minutes

Suggested Use

  • This set of activities works well near the end of the unit.

IMPLEMENT

  • Before beginning this activity, make sure students have comprehensive knowledge of the eye's lens. The purpose of this activity is to learn how glass or plastic lenses interact with the lens of the eye.
  • Depending on the age and sophistication of your students, you may choose to ignore or explore the light-ray diagrams presented in the teacher's text. Students need to know a great deal about light and how it travels to understand these diagrams. At the most basic level, they would need to know that light travels in straight lines; that objects reflect light; and that when they see an object, they see light reflected from that object.
  • Try to use lenses that are from and fit into eyeglasses.
  • Try to select a common object that is both easy to draw and contains letters or numbers. Examples include a watch, a pencil, and a battery.

Conclude GroupWork 4 by asking the following questions:

  • How does a microscope or telescope work? What kinds of lenses are found in each?
  • What are some reasons people may refuse to wear glasses or contacts? Do these reasons change with age?
  • What are advantages and disadvantages of using contact lenses over glasses? Eyeglasses over contact lenses?

ASSESS

Use the group data sheet, discussion, presentation, and individual report to assess if students can

  • compare and contrast the shape of converging and diverging lenses.
  • describe the difference between farsightedness and nearsightedness.
  • explain how lenses correct the problems of farsightedness and nearsightedness (how glass or plastic lenses interact with the lens of the eye).

Extend GroupWork Activity 4 by

  • discussing the following question: Glasses and contacts are a form of technology. What are other examples of people refusing to use technology?
  • using this activity as an introduction to the physics of light.

GroupWork 4: Activity Guide - The Way Lenses Work (Student Reproducible)

Big Idea: What Makes the Visual System a System?

For many people, the world can be a fuzzy and confusing place. Without glasses or contact lenses, they have a hard time reading, seeing a movie, or riding a bike. In this activity, you learn more about how lenses help people to see.

Materials

  • Several converging and diverging lenses and a common object.

Procedure

1. In your group, complete the following:

  • Examine the lenses. How does the shape of a converging lens differ from a diverging one?
  • Examine an object using the lenses. How does an object appear when seen through a converging lens? A diverging lens? Draw each on the group data sheet.
  • What is farsightedness? Nearsightedness? Which type of lens is used to correct each problem? How do you know?
  • For people that wear glasses or contacts, how do these lenses interact with the lens of the eye?

2. Your group has been asked to give a presentation to the third grade class at a nearby school. Some of these third graders have glasses but refuse to wear them. Your task is to explain how eyeglasses and contact lenses work and how students could benefit from wearing them. Be sure to include the following in your lesson:

  • the difference between farsightedness and nearsightedness.
  • what type of lens is needed and why.
  • reasons to wear glasses.
  • diagrams or props to help you explain.

GroupWork 4: Data Sheet - The Way Lenses Work (Student Reproducible)

Big Idea: What Makes the Visual System a System?

1. Sketch an object as seen with a converging lens.

2. Sketch the same object as seen with a diverging lens.

Groupwork 4: Resource - The Way Lenses Work (Student Reproducible)

Big Idea: What Makes the Visual System a System?

Converging and Diverging Lenses

Converging lenses are thicker in the center than at the edges. Converging lenses can make an object look upside down or right side up, smaller or bigger. The type of image a converging lens produces depends on how far the lens is from the object.

Diverging lenses are thinner in the center than at the edges. They always make objects look smaller.

Nearsightedness versus Farsightedness

Jerome can see objects clearly that are close. However, he cannot read freeway signs or identify a person across the street without his eyeglasses. People like Jerome, people who cannot see distant objects clearly, are called nearsighted. Jerome is nearsighted because the diameter of his eye is too long or his lens is too thick. In either case, faraway images are always focused in front of the retina and appear blurry. However, Jerome can hold an object closer to his eyes and see a more detailed image of that object than a person with normal vision can. In this sense, being nearsighted is like having a built-in magnifying glass.

Allison has a different problem than Jerome. She can see faraway objects, like a movie screen, clearly. However, she cannot read a book or newspaper without her eyeglasses. People like Allison, people who cannot see close objects clearly, are called farsighted. Allison is farsighted because the diameter of her eye is too short or the lens is too thin. In either case, to focus on objects far away, she must accommodate her eyes, thickening the lens so that the image hits the retina. Thus, while a person with normal vision has her or his eyes relaxed when viewing distant objects, Allison must accommodate hers. Her eyes, then, can never accommodate enough-the lens can never get thick enough-to focus on close objects. The images of close objects are always focused behind the retina and appear blurry.

GroupWork 4: Individual Report - The Way Lenses Work (Student Reproducible)

Big Idea: What Makes the Visual System a System?

1. Describe two differences between converging and diverging lenses. When would you use a converging lens? A diverging one?

2. Ms. Row has difficulty reading the morning newspaper. What type of lens does she need to correct her vision? Why?

3. Nicole is nearsighted but will not wear her glasses. Is this a problem? Explain.

GroupWork 5: Teacher Activity Notes - The Versatile Eye

Big Idea: What Makes the Visual System a System?

PLAN

Summary In this activity, students conduct an experiment to explore the relationship between the structure and function of the retina. They then create a model of the retina to explain their findings to the class.

Group Size 4 to 5 students

Objectives

Students:

  • identify the structure and function of the retina.
  • describe how changing the retina's structure affects the rest of the visual system.

Student Materials

Colored, white, and black squares of paper; dark sunglasses; a black felt pen; poster paper; and art supplies.

Multiple Abilities

  • Reasoning ability (making connections between ideas/concepts, logically analyzing a problem)
  • Spatial/visual ability (drawing an idea, creating a model)
  • Ability to be precise (recording data correctly and clearly, measuring accurately, explaining clearly and fully, observing carefully and accurately)
  • Creativity (generating alternatives)

Estimated Time 40 minutes

Suggested Use

  • This set of activities works well near the end of the unit.

IMPLEMENT

  • Try to use those glasses given to people who have had their eyes dilated-glasses that are very dark and that wrap around.
  • Students need to be familiar with the structure of the retina, the difference between rods and cones, and how they see at night in order to successfully complete this activity. You may or may not choose to include the two resource cards that review some of this information.

ASSESS

Use the group discussion, presentation, and individual report to assess if students can

  • identify the structure and function of the retina.
  • describe how changing the retina's structure affects the rest of the visual system.

Extend GroupWork Activity 5 by asking the following questions:

  • How many students have difficulty seeing clearly at night? Why is this a common problem?
  • How does vitamin A deficiency cause night blindness?
  • Many mammals are nocturnal. What kind(s) of receptors do they have in their retina? Why?

GroupWork 5: Activity Guide - The Versatile Eye (Student Reproducible)

Big Idea: What Makes the Visual System a System?

Why can't we see things clearly out of the corner of our eye? Why do we see things differently at night? In this activity, you explore how the structure of the eye affects its function.

Materials

  • Colored, white, and black squares of paper; dark sunglasses; a black felt pen; poster paper; and art supplies.

Procedure

1. Using the materials at your table, devise an experiment to investigate people's field of view. Find out how people see colors and words differently when

  • looking straight ahead versus peeking from the corner of their eye.
  • staring at a stationary object versus tracking a moving target.
  • viewing objects during the day versus at night.

Record your observations in your journal. Summarize your findings in a diagram.

2. Research the structure and function of the retina. How is what you've read about the retina related to your findings?

3. Now, as a team, use what you have learned in this activity to create a model of the retina. For your presentation, use the model to explain the following:

  • In what ways is the eye versatile?
  • How does the retina's structure make it versatile?
  • How would changing the retina's structure affect the rest of the visual system? Affect what you were able to see?

Groupwork 5: Resource 1 - The Versatile Eye (Student Reproducible)

Big Idea: What Makes the Visual System a System?

Field of View

Your field of view is made wide by the presence of two eyes. On average, humans have a field of view of 208 degrees.

Diagram of Field of View:

GroupWork 5: Resource 2 - The Versatile Eye (Student Reproducible)

Big Idea: What Makes the Visual System a System?

The Retina: Inspector Versus Detector

The retina is designed to do two jobs: examine detail and detect motion. To do so, it is divided into two regions. The first region of the retina is the inspector. It is the area we use when we want to see an object clearly. This region is less than half a millimeter across and is concentrated with cones. It is called the fovea. Why does the fovea provide such a clear picture? First, most of the processing cells and blood vessels have been cleared out of the fovea. This arrangement allows light direct access to the cones there and prevents its scattering. Second, cone cells in the fovea make a one-to-one connection with the processing cells in the outer layer of the retina. This one-to-one connection relays a point-by-point image to the brain. For these two reasons, the fovea produces a clear, crisp image.

The rest of the retina is the detector. It detects movement and boundaries along the edges of our field of view. This region consists mainly of rods and provides us with a blurry image. It is called the peripheral retina. Why does the peripheral retina produce a blurry image? First, blood vessels and processing cells scatter the light before it reaches the rods. Second, more than 125 rods feed information into one processing neuron. This processed image is then transmitted to the brain. For these two reasons, our peripheral retina produces blurry images.

The Retina: Day Versus Night

What happens to colors at night? During the day, we see colors because the cones of our retina are active. The cones have high thresholds. In other words, they respond only to high levels of light. Because cones come in three types-blue, red, and green-they allow us to see color. At night, we use rods to see. Rods have low thresholds. They are hundreds of times more sensitive to light than cones. In weak light, rods will send signals to the brain while cones will not. However, rods come in only one type. All rods absorb violet-blue light. Thus, they cannot provide the brain with information on color. That is why, in dim light, everything appears black, white, or gray.

Why is our vision at night often blurry? We learned part of the reason above. During the day, we use our cones to see. Our cones are concentrated in the fovea-the only part of the retina to produce a clear image. Moreover, in bright light, the pupils of our eyes are constricted. This reduces the number of light rays entering the eye and limits those that do enter to passing through the center of the lens. These two factors allow the eye to focus a clear image. Unfortunately, we cannot use our fovea in dim light-it does not contain enough rods. Instead, we must use our peripheral retina, which transmits processed images to the brain instead of point-by-point ones. Furthermore, the pupil cannot remain constricted in dim light. Not enough light would enter the eyes. Instead, the iris opens and the pupil dilates. Light that enters passes through a larger area of the lens. The lens bends light more at its edges than in its center. The difference in bending contributes to the making of a blurry image.

GroupWork 5: Individual Report - The Versatile Eye (Student Reproducible)

Big Idea: What Makes the Visual System a System?

1. What happens to the color of objects at night? Why?

2. In creating your model of the retina, what are two pieces of information you used from your experiment? Two pieces of information you used from the resource material?

3. How is the eye versatile? Give at least two reasons.

4. How would changing the structure of the retina change what you were able to see? Provide one specific example.

Groupwork 6: Teacher Activity Notes - Looking into the Future: The Bionic Eye

Big Idea: What Makes the Visual System a System?

PLAN

Summary In this activity, students study the eye as an organ in the visual system. They design a bionic eye and attempt to sell their design to a company.

Group Size 4 to 5 students

Objectives

Students:

  • identify and describe the function of the parts of the eye.
  • explain how the parts of the eye form an organ.
  • describe how the human eye can be improved.

Student Materials

Art supplies

Multiple Abilities

  • Artistic/creative ability (thinking of new uses for familiar objects, conceiving of an idea for an illustration)
  • Spatial/visual ability (drawing an idea, creating a model)
  • Ability to make plans (organizing group, breaking tasks into its parts, focusing on a goal)
  • Communication skills (explaining clearly and fully, using words precisely)

Estimated Time 40 minutes

Suggested Use

  • This set of activities works well near the end of the unit.

IMPLEMENT

  • Students need to be familiar with the structures of the eye and their functions.
  • Schedule time for the presentation.

Conclude Groupwork Activity 6 by asking the following questions:

  • What happens when one part of the eye is damaged? How does this situation help answer the question: How is the eye an essential organ in the visual system?
  • How do the eyes of other animals differ from those of humans? If you don't know, how could you find out? What might account for similarities and differences between the eyes of different animal species?
  • Would you like to work for a biotechnology firm someday? Do you know someone who already does?

ASSESS

Use the group discussion, presentation, and individual report to assess if students can

  • identify the parts of the eye-their separate functions and how they work together.
  • explain the functions of the eye within the visual system.
  • describe how the human eye can be improved.

Extend GroupWork Activity 6 by

  • inviting someone from a local biotechnology firm to speak to the class about his or her work.
  • having students research a technological innovation intended for use in the human body. Examples include pacemakers, hearing aids, and artificial limbs. How does this innovation work? How does it interact with the rest of the human body?
  • Discussing the costs and benefits of using technology to enhance or extend human life. Are there examples in which technology should not be used?

GroupWork 6: Activity Guide - Looking into the Future: The Bionic Eye (Student Reproducible)

Big Idea: What Makes the Visual System a System?

Examine the eye of a teammate. Why is there a black dot at the eye's center? What does the colored part do? In this activity, you take a closer look at the structure and function of the eye. You learn how the eye's parts work together to allow you to see.

Materials

  • Art supplies

Procedure

1. In your group, discuss the following questions:

  • What are the different parts of the human eye?
  • Which do you think is the most important part ? Why? Is there one right answer?
  • What are the functions of the eye within the visual system?

2. Your team has just been hired by EyeTech, Inc., a company that designs and produces bionic components. Your task is to create a new and improved human eye. Draw or build a model of an improved human eye and present it to the Board of Directors of EyeTech.

Your presentation should include the following:

  • the improvements you made to the eye and reasons why you made them.
  • reasons the company should accept and pay for your design.
  • an example of an advertisement (a jingle, a billboard, a TV ad) for the new eye.

REMEMBER, the future of the company is in your hands!

Groupwork 6 : Resource 1 - Looking into the Future: The Bionic Eye (Student Reproducible)

Big Idea: What Makes the Visual System a System?

GroupWork 6: Resource 2 - Looking into the Future: The Bionic Eye (Student Reproducible)

Big Idea: What Makes the Visual System a System?

GroupWork 6: Individual Report - Looking into the Future: The Bionic Eye (Student Reproducible)

Big Idea: What Makes the Visual System a System?

1. What do you think is the most important part of the human eye? Why?

2. What two improvements did you make to the human eye? Why did you

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