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OH, SAY CAN YOU SEE
by Nancy Orme
University of Idaho Student

GRADE: 9 to 10

SUBJECT MATTER: Life Sciences: senses, The eye

TIME ALLOTMENT: Three 70 minute periods

OVERVIEW
This lesson will explore the anatomy of the eye. Students will explore different parts of the eye and functions of each part through a video and a dissection of a cow’s eye. Students will discover different causes of blindness.

LEARNING OBJECTIVES

Students will:

  • Label a diagram of an eye.
  • Define the function of each part of the eye (cornea, lens, pupil, iris, retina, optic nerve).
  • Describe the functions of the rods and cones. Identify parts of the cow’s eye.
  • Research reasons for blindness and write a 2 page paper on a chosen cause.

STANDARDNational Science Education Standards http://www.nap.edu/readingroom/books/nses/html

  • Content Standard A Science as Inquiry Content
  • Standard C, Life Science Structure and function in living systems Diversity and adaptations of organisms
  • Content Standard F, Science in Personal and Social Perspectives Personal Health

PREP FOR TEACHER

  • Obtain TV/VCR for class period.
  • Order cow’s eyes at least three weeks prior to class period. If you obtain them from a butcher’s shop try to get eyes with the muscles and fat still attached. Get the eyes the day of the dissection because fresh eyes are easier to cut. Ensure dissection tools are available as well as clean up materials.
  • Obtain overhead projector.
  • Produce transparencies, diagram handouts with and without labels, lab procedure and write up, and individual teacher’s own rules and expectations.
  • Copy and cut apart these words :Corneal diseases, Glaucoma, Albinism, Cataracts, Retinal diseases, Optic nerve damage, Brain damage, Microphthalmia, Anophthalmia, Corticle visual impairment, Coloboma, Cerebral palsy, Cornelia de Lange Syndrome, CHARGE Syndrome, Mitochondrial disease, Septo-Optic Dysplasia

MATERIALS

For an average class of 24:

MEDIA COMPONENTS

Video
Eyewitness 304-Sight
“This episode reveals the world through new eyes. All creatures have eyes for the job-from the action-packed vision of the dog to the tiny shrimp that see colors beyond human imagination. This spectacular program takes viewers through a world of illusion, a realm where there is much more to see than meets the eyes.” (http://idahoptv.org/itv/eyewitness.html )

WEB SITES

This site will enhance your experience of dissecting the eye. http://www.exploratorium.edu/
learning_studio/cow_eye/index.html

This is a very thorough site about the eye designed by students. http://library.thinkquest.org/C001464/
cgi-bin/main.cgi?

This site has an eye tutorial which includes a section on diseases. http://numedsun.ncl.ac.uk
/~nds4/tutorials/eye/index.html

This site lets you see the world through the eyes of a bee. http://cvs.anu.edu.au/andy/
beye/beyehome.html

PREVIEWING ACTIVITIES

Guided Imagery Have everyone close their eyes and completely relax (turn off lights). Tell them to imagine the most beautiful place they have been. Think of the lights, the brilliant colors, the people present. Who is with you? What do they look like? What are they wearing? What are you doing there? Keep this image in your mind and open your eyes (turn lights on).

VIEWING ACTIVITIES

Step 1. With the previous image in your minds, how would you feel if you are no longer able to see? Why? Do you feel sad and/or angry? How does the eye work? Discuss students’ concepts of vision. The brain perceives light and images.

Explain what they will see on the video. Go over the FOCUS FOR MEDIA INTERACTION

The students will complete the FOCUS FOR MEDIA INTERACTION worksheet as they watch the video.

Start video presentation Eyewitness 304-Sight (30 minutes). PAUSE at the eagle. Answer the worksheet. Check for understanding and answer any questions. START Continue until the discussion ends about “Take light in”. PAUSE

Complete the vocabulary definitions on worksheet. Look at the next questions so the students can look for the information needed to answer them. START and watch until just after the fly. PAUSE Discuss the compound eye. Fill in the worksheet. START . PAUSE after the blue glasses. Discuss how the color of an object is determined.

CONTINUE until after you see the camels in the desert. PAUSE Discuss the mirage. CONTINUE until the end. Complete the worksheet.

Step 2. Discuss the following: What are the parts of the eye? Use overhead diagram and have students look at their neighbors’ eyes. (Cornea, Lens, Pupil, Iris, Retina, Optic nerve) What makes each part important? How does each function help us see? Have students discuss what they think the function is. (leave overhead up)

  • Cornea— The transparent, convex, anterior portion of the outer fibrous coat of the eyeball that covers the iris and the pupil and is continuous with the sclera. It protects the eye.
  • Lens— A transparent, biconvex body of the eye between the iris and the vitreous humor that focuses light rays entering through the pupil to form an image on the retina.
  • Pupil— The apparently black circular opening in the center of the iris of the eye, through which light passes to the retina.
  • Iris— Colored part of the eye that controls the amount of light that enters the eye.
  • Retina— A delicate, multilayered, light-sensitive membrane lining the inner eyeball and connected by the optic nerve to the brain. Part of the eye where light-sensitive receptor cells called rods and cones are located.
  • Optic Nerve— Either of the second pair of cranial nerves that arise from the retina and carry visual information to the thalamus and other parts of the brain.

Have students turn to their neighbor at their table. Have them take turns closing and covering their eyes for 30 seconds and have their neighbor observe their pupil size change. Ask the students “Given what we have discussed, why does your pupil change?”

To adjust the amount of light entering the eye, give each student a piece of paper with a cross and a dot on it. Have each student close one eye and focus on the dot with the other eye (the cross should be to the outside of the face). Slowly bring the paper closer to them and notice how the cross will disappear. This is the blind spot. What causes a blind spot? It's the point where the optic nerve leaves the eye.

Ask the students “How come we don’t notice our blind spot on a daily basis?” The answer: We have two eyes and one compensates for the others blind spot. Ask the students “Now that you know how light is passed through the eye, how does your brain perceive colors and images?” (use transparency of rods and cones, brain)

  • Rods— Photoreceptors concerned with colorless vision in dim light.
  • Cones— Photoreceptors concerned with color vision in ample light.

Step 3. What is perception? Why do people perceive the same things differently? Sight is an amazing ability. Why, then, are some people without sight? What causes blindness? (Corneal diseases, Glaucoma, Albinism, Cataracts, Retinal diseases, Optic nerve damage, and Brain damage. Other eye conditions are Microphthalmia, Anophthalmia, Corticle visual impairment, and Coloboma.. Additional disabilities include Cerebral palsy, Cornelia de Lange Syndrome, CHARGE Syndrome, Mitochondrial disease, and Septo-Optic Dysplasia.)

Tell the students that “I have each of these causes in a hat. I will walk around the room and I want each student to choose one and write a 1-2 page paper on this cause of blindness.” They should have three days to do this. Tell them to be sure to answer the questions: How does it cause blindness? What part of the eye is affected?

POST VIEWING ACTIVITIES

CULMINATING ACTIVITY
Step 1. Have the class split into groups of two. Hand out lab procedure and go over with the students. Give each group one cow’s eye and one dissection kit. Guide students through dissection, making sure each student is participating and understanding what they are observing. Clean up.
Step 2. Research causes and perhaps cures, of blindness. Choose one and write a 2 page paper exploring the topic. Explain your expectations such as correct grammar , spelling, references, form, deadine.

ACTION PLAN

STUDENT ASSESSMENT Students will be tested over the material covered in class. Identification of eye parts on a diagram. Teacher will label parts of an eye with numbered pins. Students will identify the part orally or on paper. Identification of cow eye parts. Ability to describe the function of they eye and all of its parts. Ability to describe the functions of the rods and cones. The research paper.

EXTENSIONS

Physics:
Complete a unit on light at the same time.

Cross Curricular Extensions:
This will be included in the discussion of the eye and perception, which is usually studied in Psychology.

Community Connections:
The students will have a better understanding of blindness and a greater appreciation for their ability to see. Through this, I hope to instill in students a respect for those who are blind in our community.

For additional lesson plans and ideas relating to this topic and many others try TeacherSource at PBS Online! You will find activities, lesson plans, teacher guides and links to other great educational web sites! Search the database by keyword, grade level or subject area! Mathline and Scienceline are also great resources for teachers seeking teaching tips, lesson plans, assessment methods, professional development, and much more!

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