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This is a lesson designed to review the parts of the human eye and understand how the eye and the mind work together to form optical illusions. This lesson can cross the science curriculum into art, math, language arts, drama and careers, to name a few.

Students will be actively involved studying the parts of the human eye and identifying their functions, looking at and creating unique optical illusions, developing a hypothesis for the existence of optical illusions and questioning an eye doctor as a guest speaker.

Students will create dodecagons which are twelve-sided figures with twelve equal angles and share these with the class so that each student can begin to see how many different illusions can be created within the same set of boundaries.

The length of this lesson can run anywhere from 2-5 class periods depending on the number of Extension Activities and Action Plans utilized.
ITV Series
READING RAINBOW #801: "Opt.. An Illusionary Tale"
Learning Objectives
At the end of this lesson the student should be able to:
Pre-Viewing Activities
To immediately focus student attention ask, "Who can name any part of the human eye?" List all of their answers on the board or overhead. Because most students will not know the answers you might want to do some prompting here.

"O.K., I have a picture of the human eye on the overhead with a list of eye parts and I would like you to raise your hands and tell me where to place these names on the picture." Have the students come up to the overhead and actually write in their answers.

After filling in all of the blanks on the overhead, hand out a copy of the eye to each student and have the students fill in the correct words so that they will each have an accurate copy of the human eye. "Please copy the correct answers from the overhead to your diagram so that you will have an accurate study sheet."

Hand each student a vocabulary sheet and have the students write in the definitions following a short discussion of each term. "Here is a list of vocabulary words concerning the human eye. I will choose a term on the sheet and call on one of you to give an educated guess as to its particular function. Susan, what is the purpose of the retina? Yes, everyone please copy down this definition for retina. . . ."

Continue calling on the students until all of the terms have been defined. "Now that we know the parts of the eye and their functions, who can define optical illusion? Good, John, optical illusions are visual tricks that are played on the mind."

"Who can tell me a specific optical illusion you have seen? I'll start you off with the old lady, young lady. Now, who else has one?" Begin a brainstorm list on the overhead, writing down all appropriate answers.

"Later in the week we'll have an eye-doctor come as a guest speaker to explain and show how the human eye works and why we see optical illusions."

"Right now we are going to watch a video called, "Opt. . .An Illusionary Tale" about optical illusions. I'm going to have each of you watch and listen for several key items so. . .let your eyes and ears do the talking."
Focus Viewing
To give the students a specific responsibility while viewing:

Ask students to listen for the definition of horizontal line.

Ask students to listen for the definition of vanishing point.

Ask the students to identify four tools of a TrumpLoi artist.

Instruct students to raise their hands once they hear the answers for the above questions.

Viewing Activities

BEGIN the video where LeVar Burton is holding a spinning red and white bull's eye. This is after he shows how to make an indoor snow storm.

PAUSE the video on the picture of two cats on the fence. Let students really look at the painting and begin showing them all of the parts of the painting that look so real. This is a precursor for the next pause point when TrumpLoi is defined. RESUME the video.

PAUSE the video on the picture of jewelry to let the students write the definition for TrumpLoi (French word for, trick the eye). Students should have raised their hand for you to pause here. RESUME the video.

PAUSE the video on the close-up of the blackbird. Ask the students what really makes the bird look real. (You should get responses regarding shading, shadow, three-dimensional etc.) Ask the students if they have seen any paintings like this and lead a discussion accordingly. RESUME the video.

PAUSE the video on the Horizon Line Definition so that the students can copy this definition in their notes. The students should have raised their hands here. RESUME the video.

PAUSE the video on the Vanishing Point Definition so that the students can copy this definition in their notes. This also comes from the Focus For Viewing section. RESUME the video.

PAUSE the video when the guest artist says, "Here's a pair of railroad tracks that are going to disappear right into the horizon." At this point hand each student a piece of typing paper and have them take out a ruler and pencil so that they can draw the railroad tracks right along with the artist on the video. At this point the teacher must pause the video according to the students' speed of drawing and some rewinding might need to be done to insure that all students are accomplishing disappearing tracks. RESUME the video.

PAUSE the video when the guest artist says, "The railroad tracks get closer together. . ." Have the students continue drawing the tracks, copying the video picture. RESUME the video.

PAUSE the video when the artist says, "We could add telephone poles. . ." As the students draw the telephone poles, help them connect the vanishing points. Rewind the video until all students have finished. RESUME the video. PAUSE the video when the artist says, "Creating illusion of distance. . ." Have the students look at their own drawing and compare with the video. Have several students share their artwork with the class, continuing to stress vocabulary words. Ask the students what creates this illusion. RESUME the video.

PAUSE the video when the artist says, "Most important tool of all is imagination." Discuss with the students the importance of imagination and art and optical illusions. RESUME the video (Let the next video segment continue without interruption).

PAUSE the video when the artist says, "Is basically what fools the viewer." Discuss with the students any thoughts of how real the door handle looks. RESUME the video.

PAUSE the video on the picture of the shutter doors. Ask the students about how real the shutter door looks and what causes the mind to think it is real. RESUME the video.

PAUSE the video on the picture of the lights of the ferris wheel. Have the students guess how this was accomplished. RESUME the video for the answer. STOP the video when LeVar Burton comes back into view.
Post-Viewing Activities
After viewing the video and making general comments the students will take notes and discuss the five major categories of Optical Illusions, while viewing samples of each one.

Using the overhead titled Categories of Optical Illusions, have the students copy these definitions into their notes and show examples of each category. These examples can be found in any book about optical illusions or you may use the bibliography at the end of this lesson. Discuss each category thoroughly.

Then, split the class into five small groups representing each of the five main categories of optical illusion. Each group must create their own illusion using all of their newly gained knowledge. Their illusions must be backed up with a unique hypothesis explaining why their new illusion tricks the mind. The students may include in their hypotheses things such as: functions of the eye, perspective, experience, color, etc.

Give each group no more than two class periods to complete this task. After all illusions have been created have the groups present their findings to the class and lead a discussion following each presentation. During this part of the lesson you might want to review vocabulary, look at specific examples, re-watch parts of the video, etc.

Next, to assess student learning I have the students write a one-two page essay answering the question, "What is Optical Illusion?" The students are allowed to use their notes and any visual aids that they have such as books, articles or pictures of optical illusions. This evaluation really lets the students state their opinions and it gives them a chance to back up their thoughts with their notes.

Finally, to bring in the math side of illusions have the students create dodecagons in the following manner.

Ask the students, "Does any one know what the root word for twelve is? If you can think of a math term it might help. Yes, Bob, dodeca means twelve and a dodecagon is a twelve-sided figure with twelve equal angles. Now then, Karen, tell me how you think a dodecagon ties in with optical illusions. Yes, if dodecagons are created as symmetrical figures with shading they become optical illusions because it's difficult to tell where each individual dodecagon begins and ends. And, if you change the pattern slightly the illusion completely changes."

At this point, hand the students a copy of the 63 dodecagons worksheet and discuss with the students the different patterns and have them first draw one that is listed and finally, have each student create a new repeating dodecagon that creates an illusion of some sort.

First, have the students each draw a twelve-sided outline that is fairly large so that they will have room to work. Next, have each student begin drawing a dodecagon that is from the worksheet so that they begin to see what makes a dodecagon turn out equal. Remind students that they may only use straight lines although the lengths may vary. Walk around and assist students as necessary.

When students have completed this dodecagon, have them begin creating their own design within a twelve-sided figure. Tell the students that their design must be repeated in at least 10 connected dodecagons so they should create a center design that is repeatable. Also, it is recommended that students either color their dodecagons or shade them in with pencil so that the illusion in more noticeable.

After all of the students have finished this assignment, have them share their creations with the class so that each student has a chance to see the different illusions developed with the same twelve-sided boundary.
Action Plan


Kettelkamp, Larry. Tricks of Eye and Mind. William Morrow and Company. New
York. 1974. Mueller, Conrad, G. and Mae Rudolph. Light and Vision. Time Incorporated. Life
Science Library. New York. 1966.
Simon, Seymour. The Optical Illusion Book. Four Winds Press. New York. 1976.
Ward, Brian W. The Eye and Seeing. The Human Body. Franklin Watts Limited. New
York. 1981.
Wertenbaker, Lael. The Eye: Window to the World. Torstar Books. New York. 1984.
Lesson plan created By Kendra Ruwe Clark, Lowell Scott
Middle School, Meridian, Idaho

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