Do Humans Have Blind Spots?

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Student worthiness
Tested and Worked.

Primary biological content area covered

 * Scientific Method
 * Structure of the eyeball
 * Human Body Systems (Nervous System)
 * Experimental Design

Materials
Materials Required for Teacher's Use: (Figure 1)
 * Labeled diagram of the eyeball (see Eye Diagram for Coloring Teacher's Key)
 * Explanation of what the blind spot is, why we have a blind spot, and the role the eyeball plays in the nervous system (see Eye Diagram for Coloring Teacher's Key)
 * The Magic Anatomy Book

Materials Required for Each Student: (Figure 2)
 * Blind Spot Tester
 * Diagram of the eyeball
 * Markers or Crayons

Handouts
Students will receive the Blind Spot Tester and the Diagram of the Eye hand-out, which they will color in as the parts and functions of the eye are discussed. Eye Diagram for Coloring Teacher's Key

Description of activity
The blind spot is the area on the retina without receptors that respond to light. Therefore, an image that falls on this region will NOT be seen. It is in this region that the optic nerve exits the eye on its way to the brain. Students will determine their blind spot by shifting the blind spot tester within their range of vision. Students will also learn the function of the parts of the eyeball, as well as the role the eyeball plays in the nervous system.

Lesson plan

 * Ask the students what they know about the eyeball, and if they are familiar with different parts of the eyeball. Also, ask them if they know the function the eyeball plays in the nervous system of the human body.
 * Using the Diagram of the Eye teacher's key, go through each part of the eyeball and describe its function. Then, have the students color the part of the eye being discussed on their diagram. For example, letter C is the cornea. Have the students observe where letter C is on their diagram, explain the role the cornea plays in the eyeball, and then have the students color in the cornea on their diagram. Be sure to have the students use a different color marker or crayon for each part of the eye (Figures 3, 4 and 5).
 * After you have discussed the location and function of the different parts of the eye, have the students use the scientific method to hypothesize whether they believe that humans have a blind spot or not. Once the students have formulated a hypothesis, have them follow through with the experiment to determine whether the hypothesis was supported or rejected.
 * Students will pair up. One student will hold the blind spot tester, while the other receives the blind spot test.
 * The student receiving the blind spot test will first close his/her right eye. Then, the student giving the blind spot test will hold the blind spot tester about 20 inches away from the student receiving the blind spot test's face (Figure 6).
 * The student receiving the blind spot test will look at the :-) symbol with their left eye.
 * Slowly, the student giving the blind spot test will bring the image closer to the student receiving the blind spot test's head, as the student receiving the blind spot test continues to look at the :-) symbol. At a certain distance, the dot will disappear from their peripheral vision. This is when the dot falls within the blind spot of the retina, and the student receiving the blind spot test has determined his/her blind spot.
 * Have the partners switch roles, so that the student who was receiving the blind spot test is now giving the blind spot test, while the student who was receiving the blind spot test is now giving it.
 * Have the student who is now giving the blind spot test perform the same actions upon the student who is receiving the blind spot test as previously performed.
 * Students will now determine whether their hypothesis was supported or rejected.
 * Note: Once the students have finished the experiment, the students will look at the pictures in Chapters 8 and 9 of The Magic Anatomy Book.

Potential pitfalls
Some difficulties that must be brought into account are, for one, that the teacher should be sure to write a word bank on the board. As the teacher goes through each letter: explaining to the students which part of the eye ball it is, it's location, and the role it plays as part of the eye; the teacher should be sure to write the parts on the board, so that the students can write their own word bank on their diagram. This way, the students are saying the part out loud, coloring it in, and then writing the word out themselves in order to increase their ability to recall the part in the future. Another difficulty is dealing with the frustration of a couple of the children over the fact that they could not find their blind spot. Some ways to appease this difficulty is by having them close their left eye instead of their right and look at the :-( symbol. This way, they may be able to find their blind spot in their right eye. Allow the students to take home their blind spot tester so that they can try it out on their parents and friends.

Artistic Connection
As the students label their diagraim, they will use a variety of colored markers in order to distinguish the different parts of the eyeball. By using different colors, the students will more readily be able to identify the individual parts. For example, a student may choose to color the pupil blue and the lens red so that they can easily find where they are located.

Literature connections

 * Cole, Joanna. Magic School Bus Explores the Senses (Magic School Bus Series). New York: Scholastic Inc, 1999.
 * Donner, Carol. The Magic Anatomy Book. New York: W.H. Freeman and Company, 1986.
 * Smith, Penny. First Human Body Encyclopedia (DK First Reference Series). New York: Dorling Kindersly Limited, 2005.

Chapter Eight, beginning on page 63, has a lot of information on the structure of the eye, while Chapter Nine, beginning on page 72, has a lot of information on the role the eyeball plays in the nervous system!

Connections to educational standards

 * 1) S3-4:41 Students demonstrate their understanding of human body systems by showing connections between external and internal body structures and how they help humans survive.
 * 2) S3-4:5 Students demonstrate their ability to REPRESENT DATA by… Classifying objects and phenomena into sets and subsets and justifying groupings...Displaying and labeling data for separate trials/observations.

Next steps
Once this activity is completed, a teacher can examine a more in-depth study of vision. The teacher can explore a greater understanding of the nervous system and the role it plays in sustaining human survival. Some other activities that can be developed involve optical illusions and experimenting with depth perception.

Reflections
-Ashley
 * This experiment was very successful. After learning the function and location of the parts of the eyeball, the students successfully colored in their diagram and were able to answer questions about these parts after the activity was completed. We asked the students what they learned from this experiment, and every student was able to label at least one part of the eyeball that they learned the location and function for. Furthermore, almost every student was excited upon finding their blind spot. Two or three students were not able to locate their own blind spot, but they were still excited when their peers were able to discover their blind spot. The students sent us thank you cards after their visit, and a number of students commented on the eyeball experiment being their favorite experiment. One student successfully drew a diagram that looked anatomically correct on his/her thank you card. One thing that was unexpected, in my opinion, was how much the students already knew about the eyeball. They were able to build off of this knowledge via this experiment. One "must do" component, is my opinion, is having the book on hand for the students to exam after they complete the experiment. This way, they are able to view other images/diagrams of the eyeball and identify some of the parts that they learned about throughout the experiment.
 * I found this experiment to be very exciting for the students, many had no idea that a blind spot existed in their eye. The students worked together in pairs which encouraged a sense of community and it seemed that through working in pairs the students became even more excited when their partner found their blind spot. I was surprised by the amount that the students already knew about the structure of the eye and how it functions. Asking the students to draw and label their own eye was helpful and furthered their learning. Overall I feel the experiment was very successful and I would definitely recommend it to all! -Maren

Citations and links

 * http://www.all-science-fair-projects.com/science_fair_projects/40/124/4a04c0375d0c64e528d7df34bb83af40.html


 * Science standards taken from the Vermont Department of Education website. Standards


 * A useful website on the differnt types of eyes: http://en.wikipedia.org/wiki/Eyeball
 * A useful website on the gross anatomy of the eye: http://webvision.med.utah.edu/anatomy.html