Designed by Sandra Craig, Math & Science Teacher, Kansas State School for the Blind
The purpose of this activity is to provide students with a personal model of the eye in order to study its structure and function. This activity was part of a semester long project we called Flat Stanley.
Materials & Sources
globe & cornea
2” acorn capsule
These capsules can be found at Walgreens containing knee-hi’s or by searching online.
craft foam in blue, brown and green or food container lids from nut cans (blue and green) or hot cocoa mix canister (brown)
flat, semitransparent plastic from the side of a milk jug or potato chip canister lid.
ring left on milk jug after cap is twisted off. Select one that matches the iris color. Pry off gently, leaving it intact.
(Rings from Arizona Tea bottles were a bit too large.)
long, thin rubber band or elastic cord used in making stretch bracelets.
clear acetate sheet from bakery cookie container
blue to violet mylar from a used balloon or any thin, soft plastic packaging material of similar color (such as disposable diapers packaging)
plastic coffee stirrer
first aid tape, white vinyl tape, or white duct tape
optional: vitreous humor
Look for “Slime” in toy section of dollar stores. Try to find something clear or a light colored.
Remove the knee-hi’s from the capsule and place in a ziplock bag. Carefully remove the label from the cap and apply the label to the outside of the bag. (If the knee-hi’s are unwanted, consider donating them to a women’s shelter.) Remove any remaining label adhesive with a drop of cooking oil and a paper towel. Wipe the cap clean. This is the cornea.
Begin boring a hole in the back of the capsule with the push pin. Gently increase the size, using the nail if necessary, until the hole is large enough for the coffee stirrer to fit snugly in the hole. This is the globe and the optic nerve.
Apply hot glue to the outside of the capsule where the stirrer is inserted, and also place a drop inside on top of the hole.
Using the compass and Sharpie, trace a 1” circle, 1.5” circle, and 1.75” circle onto the light-weight cardboard. Cut out the circles. They are templates for some of the other structures.
Use the Sharpie and the 1.5” circle to trace a circle onto the craft foam. Cut the circle out of the form. Use the hole punch to create a hole in the center of the foam. This is the iris with pupil.
Use the Sharpie and the 1.75” circle to trace a circle onto the acetate sheet. Cut the circle out of the acetate. This is the hyaloid membrane. Create a tab by cutting off about a 1” length of scotch tape and attaching to the edge of the acetate. Fold the tape, adhesive side to adhesive side, and stick it back to the acetate. Pinch the tab flat.
Use the Sharpie and the 1” circle to trace a circle on the blue-violet soft plastic. Cut out the circle. This is the retina. Apply a mounting square to the back of the circle, but leave the protective cover on.
To make the lens, place the cap ring (ciliary muscle) on the flat plastic from the milk jug and trace inside the ring. Cut this circle out, and trim off an additional 1/8” of the circle. Place the ring and plastic on the corrugated cardboard, and using the push pin, pierce holes in the plastic approximately 1/8” from the edge, that match up to the holes in the ring. Cut the rubber band and thread it through the needle eyehole. Whip stitch the plastic to the ring. Leave 2” tails for tying off. Trim excess rubber band.
Place all the pieces into a ziplock bag. Create one bag per student.
Handout “THE EYE” poster to each student. Offer braille versions as appropriate.
Give each student an eye model kit.
Begin the discussion the pathway of light through the eye on the way to the brain. As the discussion progresses, instruct students to remove that structure from their bag.
To Assemble the Eye (student):
Place the iris into the cap, followed by the lens and hyaloid in that order. The acetate should click in holding everything else in place. (Make sure the tab is up. This makes it easier to remove for later examination.) Set the cap aside.
Cover the outside of the capsule with the white tape. It’s easier if the tape is cut in small pieces rather than one long piece. Don’t apply tape all the way to the opening. Leave about ½” free of tape to allow for easy cap removal. Extend the tape part-way down the optic nerve.