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6.3: Activities and Answer Keys

Difficulty Level: At Grade Created by: CK-12

Activity 5-1: Using Your Sensors

PLAN

Summary Students conduct experiments to see what happens when they sort objects with and without the use of a sensor, specifically the sense of touch and the sense of vision.

Objectives

Students:

\begin{align*}\checkmark\end{align*} design and conduct experiments on the senses of touch and vision.

\begin{align*}\checkmark\end{align*} explain what happens when you lose the sense of touch or vision.

Student Materials

• Activity Data Table
• Activity Report
• Objects of a variety of shapes and sizes; gloves; blindfold; clock

Teacher Materials

• Data Table Answer Key
• Activity Report Answer Key
• Sample Data Sheet on transparency
• Optional: extra items for students to sort

Gather and organize optional materials so they are accessible to students.

Estimated Time Approximately one to two 50-minute periods

Interdisciplinary

Math Discussion of “variables” and “constants” as they relate to math and science.

Physical Education and Health Connect this activity to ways to keep the nervous system healthy.

IMPLEMENT

Introduce Activity 5-1 by discussing experimental design and the importance of the following: variable, the factor under investigation; constants, factors which remain the same throughout the experiment; hypothesis, a “best” guess, supported with reasons, for the outcome of the experiment; data, the results of the experiment obtained by observing and measuring; and conclusions, the analysis of the data that either supports or refutes the original hypothesis. It leads to a conclusion about what actually happened during the experiment and its significance. The conclusions also could include suggestions for further experiments to answer new questions arising out of this experiment.

Gloves or mittens provide an easy means for impeding the sense of touch.

A blindfold made from a scarf or towel is suitable for blocking the sense of vision.

Invite students to design another experiment investigating the loss of both sight and touch when sorting objects.

Students also can design another experiment investigating the sense of hearing. See item #4 on the Activity Report.

Steps 1-2 Groups of at least three students are best. This allows for teamwork among the sorter, timer, and recorder.

If time is limited, you can divide the class in half, with one half of the class carrying out the touch experiment and the other half carrying out the vision experiment.

You also could divide the class into thirds, with one third investigating touch, one third investigating vision, and one third investigating touch and vision combined.

Be prepared to help student groups with suggestions for the items to be counted, how to form a hypothesis, and experimental design. Hypothesis may vary but should include reasons.

Sample Hypotheses include

• I think that the sorter will sort fewer objects correctly without touch than with touch because touch receptors are the most important sense when using the fingers and hands.
• I think that there will be fewer objects sorted correctly in the dark than in the light because the sense of vision is important in helping us distinguish between shapes of objects.

Extend Activity 5-1 Brainstorm with students other ways to design this experiment. For example, students could continue sorting until all objects have been correctly sorted. Students would then record the time needed to complete sorting. Ask students to explain why this would or would not be a better approach for the investigation. During the discussion, remind students that there are many ways to approach experimental design and that collaboration, like brainstorming, is a helpful and an enjoyable part of the scientific process.

Steps 3-4 Encourage students to design their own data sheets. However, a sample data sheet is included for your reference or use. If desired, you can copy these data sheets for student use.

Steps 5-8 Check the designs and help students whose designs are approved to get started with their investigation. Make sure students record their results on their data sheets. Remind students that conclusions need to be supported by data. Conclusions also should include explanations for any discrepancies between original hypothesis and actual results.

ASSESS

Use the experimental design, implementation, analysis of results, and written responses to the Activity Report to assess if students can

\begin{align*}\checkmark\end{align*} determine and implement the key components necessary for good experimental design (hypothesis, variable, control, data table design, making and recording accurate observations, interpreting data, and stating conclusions supported by data).

\begin{align*}\checkmark\end{align*} compare conclusions with original hypothesis.

\begin{align*}\checkmark\end{align*} change or repeat the experiment to explore other questions.

\begin{align*}\checkmark\end{align*} explain the importance of touch and vision when sorting a collection of objects.

Activity 5-1: Using Your Sensors Data Table Answer Key

Title of Experiment: Touch Experiment

Hypothesis:

Hypotheses may vary. If the sense of touch is important in helping to distinguish between shapes and objects, then there will be fewer objects sorted correctly when wearing gloves than when not wearing gloves.

Results:

Time allowed for sorting: 30 seconds (seconds, minutes)

Name of objects to be sorted Number of objects sorted
Without sensor With sensor

Draw a graph to summarize your data.

Graphs will vary but could be a bar graph showing the number of objects correctly sorted in 30 seconds. In general, a lower number of objects will be sorted correctly without the sensor than with the sensor.

Title of Experiment: Vision Experiment

Hypothesis:

Hypothesis may vary. If the sense of vision is important in helping distinguish between shapes of objects, then there will be fewer objects sorted correctly in the dark than there will be in the light.

Results:

Time allowed for sorting: 30 seconds (seconds, minutes)

Name of objects to be sorted Number of objects sorted
Without sensor With sensor

Draw a graph to summarize your data.

Graphs will vary but could be a bar graph showing the number of objects correctly sorted in 30 seconds. In general, a lower number of objects will be sorted correctly with the blindfold on than when students can see.

Activity 5-1: Using Your Sensors – Activity Report Answer Key

• Sample answers to these questions will be provided upon request. Please send an email to teachers-requests@ck12.org to request sample answers.
1. What was the variable in each experiment? What was the constant?
2. Was your hypothesis correct for each of the experiments? Give reasons for your answers.
1. Touch Experiment
2. Vision Experiment
3. In your own words, summarize the results of each of the experiments.
4. How could you design an experiment to learn more about how your senses help you respond to the environment?
5. Think about the experiments you have just completed and complete the following sentences to summarize the value of each sense in helping you communicate with your environment. My sense of touch is like _____________________ that helps me to ________________________ My sense of vision is like ___________________ that helps me to _______________________

Use Your Sensors Students sit silently with their eyes closed for a few minutes, which makes it easier to focus on the other senses. They then make a list of all the things they noticed during these few minutes.

Activity 5-2: Designing and Building a Model of the Eye

PLAN

Summary Students discuss and review the structures of the human eye and how it works to help us see. They design a model eye and use their plans to construct it. Students use their models to explain the structures of the eye and their functions. They discuss how to protect the eyes from injury and disease.

Objectives

Students:

\begin{align*}\checkmark\end{align*} explain how the parts of the eye are organized.

\begin{align*}\checkmark\end{align*} state the functions of the parts of the eye.

Student Materials

• Resource
• Activity Report
• Variable, depending on student requests. Some examples might include Construction materials (as requested by students) such as construction paper; scissors; colored marking pens; string or colored yarns (to represent nerves, muscles, or eyelashes); old tennis balls or other round, hollow objects; plastic covers for margarine containers (for the lens)

Invite a guest speaker to talk to students about proper care of eyes. Consider an ophthalmologist, optometrist, nurse, or community health resource person. Your students may have a parent or friend who works in this area and could be helpful in arranging such a visit. Obtain a Snellen Chart to show students one method for checking vision.

Teacher Materials

• Activity Report Answer Key
• Large chart and/or model of the human eye
• Optional: Computer simulation showing the structure and function of the human eye

Obtain large eye diagram and a selection of materials for constructing the models.

Interdisciplinary Connection

Physical Education and Health Students discuss and identify eye protection gear for different sports. They also discuss common diseases of the eye and how they can be prevented.

Estimated Time Approximately one to three 50-minute periods

Prerequisites and Background Information

Students should have some knowledge of the structure of the human eye and how it works.

IMPLEMENT

Introduce Activity 5-2 by discussing the chart of the eye and other computer or text references about the structure and function of the eye. You may want to have some materials available to give students starting ideas for making a materials list for their eye models.

Steps 1-5 Once students have given you designs and lists of materials, decide who will provide these materials. Even if you decide that students are responsible for their own materials, you probably will want to have some generic materials available for classroom use. (See Student Materials.)

• Construction of the model eye can take place in class, or at home, depending on your time restrictions.

Step 6 When models are complete, students can share them with the class.

• Allow time for groups to give the presentations on their models to the class, to other classes, or at home. If students share at home, invite parent feedback in the form of a written note explaining what was done, how much time was spent, and any additional comments.
• You may want to have students display their models in the classroom and/or save them for future use.

Can students modify the model in order to improve the design of the eye?

Students might conduct research and use their models to discuss

• eye diseases
• eye injuries
• corrective medical procedures
• how drugs affect vision
• corrective lenses
• protective lenses

Encourage students to improve on existing designs for protective lenses, corrective lenses, and even the human eye.

ASSESS

Use the human eye model and written responses on the Activity Report to assess if students can

\begin{align*}\checkmark\end{align*} select and use materials effectively to create a realistic model of the human eye.

\begin{align*}\checkmark\end{align*} locate correctly the important parts of the eye (sclera, retina, cornea, ciliary muscles, iris, optic nerve, lens, fovea, vitreous humor, and aqueous humor).

\begin{align*}\checkmark\end{align*} use the eye model to demonstrate how the function of the different parts of the eye enables humans to see.

Activity 5-2: Designing and Building a Model of the Eye – Activity Report Answer Key

• Sample answers to these questions will be provided upon request. Please send an email to teachers-requests@ck12.org to request sample answers.
1. What is the function of the human eye?
2. Describe your model of the human eye. You may want to include labeled diagrams.
3. Trace a ray of light from the time it enters the eye until it is received by the brain. Include in your answer the parts of your model as they correspond to the parts of the human eye.
4. What are two ways your model accurately represents a human eye? What are two ways your model does not?
5. If you were to repeat this activity how would you design and construct the eye model differently.
6. Could the eye continue to function properly if one of its parts were damaged or missing? Provide one example to support your answer.
7. Using your model, explain three important actions you could take to keep your eyes healthy and safe.

Pupils in a Different Light Students observe the pupil under varying light conditions for changes in size.

What Are the Advantages of Two Eyes? Students tape a piece of paper over one eye and then play catch with a ball to illustrate the importance of two eyes in depth perception.

Eye Dominance Students check to see which eye is dominant.

A suggested response will be provided upon request. Please send an email to teachers-requests@ck12.org.

Owls are completely color-blind. What does this imply about the structure of the eyes of owls?

If you can read all the letters in the smallest line of letters on an eye chart at a distance of 20 feet, you have \begin{align*}\frac{20}{20}\end{align*} vision. What does \begin{align*}\frac{20}{40}\end{align*} vision mean?

Activity 5-3: Exploring a Mammalian Eye (Dissection)

PLAN

Summary Students use their knowledge of the structure and function of the mammalian eye to design a dissection lab (page 46 in the student edition). Alternatively students can follow a prescribed procedure for the dissection of the eye (Resource). Students compare the similarities and differences between the human eye and a sheep or cow eye.

Objectives

Students:

\begin{align*}\checkmark\end{align*} design a dissection lab for the mammalian eye.

\begin{align*}\checkmark\end{align*} carry out an accurate dissection of a mammalian eye.

\begin{align*}\checkmark\end{align*} identify the parts of a mammalian eye on a preserved specimen.

\begin{align*}\checkmark\end{align*} state the function of each part of the eye and how the parts work together to facilitate sight.

Student Materials

• Activity Report
• Resource (If students use procedure provided)
• These will vary, depending upon experimental design and materials available. In general, each lab team will need the following items:

Goggles; sheep or cow eye; paper towels; Dissection pan; Scalpel (single-edged cutting tool); Forceps; Scissors; Needle or metal probe;

Teacher Materials

• Activity Report Answer Key
• Resource (If students use procedure provided)
• Model of an eye or large diagram! chart of the eye

Determine whether students will design their own procedure or use the one provided (Resource). Order specimens in advance. Obtain fresh specimens from a butcher. Fresh specimens can be frozen. Order preserved specimens from a biological supply house, such as

Carolina Biological Supply Company, 2700 York Rd., Burlington, NC, 27215. Call 1-800-334-5551.

Delta Biological, P.O. Box 26666, Tucson, AZ, 85726. Call 1-800-821-2502

Wear gloves and rinse specimens just prior to use.

Confirm that all student materials are available and organized so they are accessible to students.

Obtain video camera, tape, and tripod if you plan to record the activity on videotape.

Estimated Time Three 50-minute periods if students design their own procedure

Two 50-minute periods if students follow the procedure on the Resource

Interdisciplinary

Physical Education and Health Discuss the importance of eye protection during contact sports.

Social Studies Students can do research to find out about eye diseases in other countries and how they are treated.

Prerequisites and Background Information

Students should complete Activity 5-2: Designing and Building a Model of the Eye.

Students need to have knowledge of the structures of the human eye and how these structures function together to help us see.

Invite a guest speaker (ophthalmologist or optometrist) to talk about diseases of the eyes and proper care of the eyes. The talk could also include information about how glasses and contact lenses help improve vision.

Invite a nurse to explain about and/or give eye exams.

IMPLEMENT

You might want to dissect a cow eye on your own following these procedures before your students perform their own dissections in class.

Remind students about appropriate lab behavior and respectful treatment of animal specimens during dissections.

CAUTIONS:

• Remind students about wearing goggles and being careful with sharp dissection equipment.
• Remind students of safety rules when working with any cutting tool Remind them that scalpels and scissors are very sharp.
• Review procedures for treating bleeding cuts on the fingers or hands.

Steps 1-3 Students will need varying amounts of help designing their dissection procedure. Students' dissection procedure should be submitted for teacher review and approval before they are allowed to proceed. You can use the more structured approach to this dissection that is found on the Resource to help guide students through the lab design process.

Steps 4-5 Team members can assume roles such as the following:

Reader (reads directions), Surgeon (makes incisions and does dissection), Assistant Surgeon (helps surgeon), Recorder (makes drawings and takes notes during dissection). Encourage students to rotate these roles to include all students in the group. Make sure students are identifying the parts of the eye correctly.

ASSESS

Use the eye dissection and completion of written responses to the Activity Report to assess if students can

\begin{align*}\checkmark\end{align*} design and/or follow a procedure to complete a dissection of a mammalian eye.

\begin{align*}\checkmark\end{align*} identify and describe the function of the major components of the eye.

\begin{align*}\checkmark\end{align*} determine similarities and differences between the human eye and a sheep or cow eye.

\begin{align*}\checkmark\end{align*} explain how the organization of the eye enables a human to see.

Activity 5-3: Exploring a Mammalian Eye (Dissection) – Activity Report Answer Key

• Sample answers to these questions will be provided upon request. Please send an email to teachers-requests@ck12.org to request sample answers.
1. Using colored pencils, record a labeled drawing of the eye.
2. What did you find to be the most interesting part of the eye? Explain.
3. What is the purpose of the eye?
4. Describe the pathway of light beginning with the cornea until the brain receives it. Indicate each part in the pathway on your specimen.
5. Could the eye continue to function properly if one of its parts were damaged or missing? Provide one example to support your answer.
6. What would happen if the optic nerve became diseased or was cut?

A suggested response will be provided upon request. Please send an email to teachers-requests@ck12.org.

Why do deer and rabbits have such oversized ear flaps? Why do you cup your hands behind your ears when you want to hear better?

How do you think the loudness of sound is communicated to the auditory cortex?

What Do You Think?

What is noise pollution? Give some examples of noise pollution in your environment, and rank them according to how much they affect you. Are all sources of noise pollution the same for everyone? What can be done in your community to reduce noise pollution?

• If you spin around in circles, you feel dizzy when you stop. Why?
• What is motion sickness? How does it relate to your ears?

When talking about the senses we typically think of the five senses: taste, smell, sight, hearing, and touch. Expand your thinking a little and see how many other senses you can think of. Do library research to find examples of animals that use different senses than we do. Write about how animals use different sources of information about the environment than we do.

• Sample answers to these questions will be provided upon request. Please send an email to teachers-requests@ck12.org to request sample answers.
1. What role do sensors play in experiencing sensations?
2. How do you know what type of sensation you're feeling?
3. What is the difference between rods and cones? What do they do?
4. In what ways does your eye work like a camera?
5. How does your ear capture sound?

Activity 5-1 Data Table: Using Your Sensors (Student Reproducible)

Title of Experiment _______________________________

Hypothesis:

Results:

Time allowed for sorting: ________________ (seconds, minutes)

Name of objects to be sorted Number of objects sorted
Without sensor With sensor

Draw a graph to summarize the results of your data.

Activity 5-1 Report: Using Your Sensors (Student Reproducible)

1. What was the variable in each experiment? What was the constant?

2. Was your hypothesis correct for each of the experiments? Give reasons for your answers.

a. Touch Experiment

b. Vision Experiment

3. In your own words, summarize the results of each of the experiments.

4. How could you design an experiment to learn more about how your senses help you respond to the environment?

5. Think about the experiments you have just completed and complete the following sentences to summarize the value of each sense in helping you communicate with your environment.

My sense of touch is like ______________________

that helps me to _______________________________

My sense of vision is like _____________________

that helps me to _______________________________

Activity 5-2 Report: Designing and Building a Model of the Eye (Student Reproducible)

1. What is the function of the human eye?

2. Describe your model of the human eye. You may want to include labeled diagrams.

3. Trace a ray of light from the time it enters the eye until it is received by the brain. Include in your answer the parts of your model as they correspond to the parts of the human eye.

4. What are two ways your model accurately represents a human eye? What are two ways your model does not?

5. If you were to repeat this activity how would you design and construct the eye model differently.

6. Could the eye continue to function properly if one of its parts were damaged or missing? Provide one example to support your answer.

7. Using your model, explain three important actions you could take to keep your eyes healthy and safe.

Activity 5-3 Resource: Exploring a Mammalian Eye (Procedure) (Student Reproducible)

Materials

• Sheep or cow eye
• Dissection pan
• Safety goggles
• Scalpel/razor blade (single edge)
• Paper towels
• Forceps and scissors
• Needle/metal probe

Procedure

Step 1 Refer to the diagram below for help throughout the dissection.

Step 2 Observe the yellowish fat covering the eye and the beige colored muscles.

Why is the eyeball covered in fat? Why does the eye have muscles attached?

Step 3 With scissors or a scalpel, remove most of the fat and muscles from the eyeball. Be careful not to cut off the white stub (optic nerve) protruding from the rear of the eye.

Step 4 Examine the white, outer layer of the eye.

This is the sclera. What is its purpose? How does it look and feel?

Step 5 In the front part of the eye, the white layer becomes colorless, transparent, and more sharply curved. (If you have a preserved eye, this area will appear blue.)

The cornea is the name of this transparent part of the eye. How does this structure help you to see?

Step 6 Next, using the scalpel or razor blade like a saw, carefully cut the eyeball in half to separate the front part from the rear part. (Use the diagram below as a guide. Try not to let the liquid inside squirt out as you cut.)

Step 7 Lift off the rear half. A jelly-like substance may ooze out or stick to the front half of the eye. Remove this jelly like material, called the vitreous humor.

Describe the substance. What function does it serve?

Step 8 Work with the front half of the eye. Carefully cut out the cornea. Lift it off. The space between the cornea and the lens is filled with a transparent, watery fluid called the aqueous humor. It may trickle out or it may no longer be present.

Compare the aqueous humor with the vitreous humor. What function do you think the watery fluid serves?

Step 9 Observe the colored, circular muscle with a hole in the middle.

What is the name of this muscle? What does it do? The hole in the center of the lens is called the pupil. What is the function of the pupil?

Step 10 Behind the iris, you can see the lens. Usually, the lens is colorless and transparent. However, in preserved eyes, it is cloudy. Examine the lens. Notice how it is attached to the eyeball by a circular band of fibers, the ciliary muscles. The lens thickens to bring images of near objects into focus. The lens becomes thin to bring more distant objects into focus.

Step 11 Carefully cut out the lens and place it on a piece of paper.

What does the lens feel and look like? Does it bounce or break when dropped? (Remember, in a living organism, the lens is colorless, transparent, and flexible.)

Step 12 Examine the rear half of the eyeball and notice the thin layer of light gray tissue. It may have folded in upon itself. This innermost layer of the eye is called the retina. It contains specialized nerve cells, including rods and cones.

What does the retina do? Where is this layer attached?

Step 13 The point at which the retina joins the optic nerve is called the “blind spot.” Why?

Activity 5-3 Report: Exploring a Mammalian Eye (Dissection) (Student Reproducible)

1. Using colored pencils, record a labeled drawing of the eye.

2. What did you find to be the most interesting part of the eye? Explain.

3. What is the function of the eye?

4. Describe the pathway of light beginning with the cornea until the brain receives it. Indicate each part in the pathway on your specimen.

5. Could the eye continue to function properly if one of its parts were damaged or missing? Provide one example to support your answer.

6. What would happen if the optic nerve became diseased or was cut?

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