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Grades 6 - 8


Sight is the most valued of the five senses and though we think we understand how to see, few truly understand the science of sign perception and how the experience influences what we see.

This lesson is a basic first encounter with the sense of sight. The video is used to provide basic visual clues and the worksheet focuses the pertinent information. This lesson is written to be easily adapted to secondary school. Notice how this lesson integrates visual references and hands-on learning with frequent changes in the type of stimulus used. The lesson takes one lecture period and adjoining lab period to complete. A pre-lesson homework assignment is also involved.
ITV Series
Our Human Body from Science Source: "The Sense of the Sight"
Learning Objectives
Students will be able to:

Pre-Viewing Activities
On the day before this exercise, ask your students to find out and record the eye color of each member of their family.

Begin the lesson by drawing two faces on the board, one without eyes. Ask the class what is missing and invite a student to draw the missing eyes. Now ask the students if they had ever seen these two particular faces before...how did they know that something was missing from the second face? Discuss the pathway the body used to solve this problem...ear to hear the question, eyes, nervous system, brain (memory-compare-decide), muscle (arm to point, mouth to speak). Direct the discussion to focus on the eyes. Ask students what they know about their eyes. Create a list of information generated by the students, include false information in the list to refer to later. Challenge obvious answers like, "We have two!" With questions like "Are you sure,? Is that true for everyone?" And bring in the plant and animal world. "Plants turn toward the suns so they must see where it is...can you underwater as fish do?"

In groups of 2-3, ask students to close their eyes, turn and describe what they see. They will probably say that they see nothing. Tell them, "Now, place your tightly cupped hand over your eyes and open them." Some students will note that they see a reddish light. Explain that the light is slightly diffused in the upper skin layers, taking on the color of blood. Darker skin may reduce or prevent this phenomenon. Review what happened. Did anyone note that they saw the inside of their eyelid or the lines on the palm of their hands? The problem is that there was not enough light, and so, there was not enough information for your eyes to work...to see. For comparison, move your mouth as you would to speak a coherent sentence, but speak so lowly that no one can hear you. Explain that his is a similar situation: you know something is there but your ears are not receiving enough information to understand what is going on.

Draw the curtains or move to a room without windows. Leave the lights on and show the three dark colored squares. Ask students to identify the brown square...they all should be able to. Now, mix up the squares while you turn of the light...holding them up again, ask you students to pick the brown one. Since there is less light, there is less information and now it is impossible to see the difference between the colors.

Now let's just do a little eye- brain exercise. Bring out the apple covered completed with the cloth or kerchief. Explain that this is a MYSTERY OBJECT. Take a good look and notice what comes into your head as you think about this object. Remove the cloth and after a few seconds, remove the object from view. Tell students not to write what they thing the object is, but to write down any ideas they have to describe the object.

Brainstorm all of the possible descriptions. Likely, the class will have a great consensus on one or two descriptors. Ask students to explain why they didn't al come up with exactly the same descriptions...after all, they all saw the same thing. Explain that even though the object was the same for all, each of us has different experiences that we use to understand visual information. Choose different examples to illustrate this concept. therefore, what you see is interpreted differently by someone else; reality, then, is only relative!
Focus Viewing
Distribute the Focus handout. Allow a couple of minutes for students to review the sheets. To provide a specific focus for their viewing, explain that they will be able to find most of the information required in the video. Tell them to enter the information into the heading on the first sheet and to write down their eye color information. Poll the class and calculate, as arranged on the handout, how many students have each variety of eye color. Using a calculator, ask students to calculate the percentage for each color and to fill out the grid on the handout.

CUE the tape to the opening graphic: "Science Source." Direct students attention to the ENERGY PATH activity on the handout and ask them to watch the video segment to discover the correct path. Press PLAY and PAUSE when you see the title, "Seeing the light" just after the narrator says, "...illuminating everything." Query the class about what they saw int he segment and specifically about the reason they saw a cloud in the water. Now, they should be able to draw arrows between each symbol to indicate the energy path. Point out that should any part of the energy path be interrupted by an obstacle or loss of energy, vision is impaired or blocked.

RESUME PLAY until you first see the crowd, before the narrator talks in this segment. PAUSE, distribute the next focus for viewing handout and ask the class what information they can see from this picture? Note that there are shapes, colors, distance, movement, shades, proportions, textures...point out that the variety of visual information distinguished by the eyes is very significant.

RESUME PLAY and PAUSE at the Sci-Fax question. Pose the question to the class. RESUME PLAY to check the answer. Review the Focus for Viewing handout and direct students to pay attention to the next segment for information on how our eyes interpret distance and color. PAUSE on the Sci-Fax questions ana ask students to predict the answer. RESUME PLAY and PAUSE as the screen fades to black after the Sci-Fax answer. Diredf students to the last activity on their handout and tell them to watch varefully for information to complete this activity during the final segment. RESUME PLAY and PAUSE on the next Sci-Fax regarding the ye communicating emotion. Ask students to predict the naser. RESUME PLAY and STOP once the answer is revealed. Give students a few moments to complete the activity, allowing them to consult in small groups. FAST FORWARD to the Instant Replay graphic toward the end of the program. Use the first part of this segment to review key points in the lesson. STOP after rods and cones are explained.
Divide students into pairs and instruct them to sit, facing one another, very close together. Line the students up along a bright window or other light source. The student facing the light covers one of his/her eyes with their hand. Students count to ten, slowly. The other student gets very close tot he covered eye and prepares to notice what happens when the hand is removed. The hand is removed and the pupil should adjust and get smaller. Reverse positions and ask students to conduct the experiment again. Have them note their observations and in groups, come up with an explanation for the pupils' activity.

Distribute the Mystery Word Vocabulary Game and the Teacher's Corner puzzles. If desired, invite each student group to design their own optical illusions.

Conduct research on sight-related inventions and create a time line of these innovations for your classroom wall.

Create a life-sized "Camera Obscura" for your class.

Calculate the stereoscopic effect using the final handout attached to this lesson.

Study "op art", the modern movement that was fascinated with optical illusion. Each student group could research a different artist from this movement and create a work in the style of that artist.

Master Teacher: Francois Cote, Mountain Lake Public Broadcasting/Plattsburgh, NY

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