STATION 1---The Blind Spot
Hold the card with the cross and "o" on it at arm length. Close one eye and Focus open eye on the cross but be aware of the "o." Slowly bring the card towards your eyes as you keep your focus on the cross. Note the distance from your eye that the card is when the o just disappears.
**the + should be on the opposite side of open eye**
QUESTIONS:
1. Did all people in your group have the o disappear at a certain distance?
2. The point where the o disappears is called the blind spot. Why do you think you can no longer see the o at this point?
STATION 2--Color Blindness
Color blindness is a sex-linked disorder (that is its found on the chormosomes where boys have XY and girls have XX) found on the X chromosome. The dominant allele is for seeing color. The recessive allele is for color blindness--the inability to distinguish between red and green.
Read all instructions before beginning. Test each person.
DO NOT WRITE ON SCORE SHEET!!!
In the binder are plates that are colored so color blind people will have trouble reading the numbers. An example of what the numbers look like are in the small book.
Place the binder about 30 m from the face of the person being tested. Have the person look at each plate from #5 to #14 for 3 seconds. The person being tested should state the number he/she sees best and a fellow group member should write down N if that # is in the normal column or R-G if in the R-G Defect column.
Count the number of N's--->If N > 8 person is normal, if N < 8 then person is R-G (Red-Green) color blind.
Repeat for each student.
QUESTIONS: (Go back and read introduction if you need help answering the questions)
1. What does Red-Green color blind mean?
2. More males than females are colorblind. From your Biology lesson on genes and sex-linked disorders, explain why this is so.
STATION 3--Optical top
Spin the top and look at the top of the top. You should begin to see certain colors at different speeds.
QUESTIONS:
1. What colors do you see?
2. Are these colors really there?
(For an explanation of how this works turn this paper over. Do not turn it over until you have completed questions!)
STATION 4--Visual fatigue
Have all members of the group stare at the slide of the red color for 30 seconds. Immediately after the 30 seconds, push down and hold button so red disappears but keep looking at the white paper you are projecting on.
QUESTIONS:
1. What do you see on the white paper?
2. Why do you think that happens?
STATION 5--Persistence of vision
Have each group member quickly rotate the pencil with the tree on it back and forth in the palm of the hand. Look at the picture drawn on the card.
QUESTIONS:
1. What do you see as you look at the picture?
2. It takes a few seconds for an image to be "erased" from the retina. From this information, why do you think the picture looks the way it does when it is moving back and forth?
STATION 6--Eye strength
Have each group member close one eye and look at a distant small object across the room. Place your finger (while you are looking with one eye) so it covers your view of the object. Now open your second eye. Repeat for the other eye.
QUESTIONS:
1. With which eye did your finger appear to move the least? (That is it appeared to stay over your view of the object when you opened your second eye) This is your strong eye.
STATION 7--The eye vs a camera
Draw two pictures, one of an eye and one of a camera. Label their parts.
QUESTIONS:
1. Which parts are similar or serve the same function in both the camera and the eye?
2. How does focusing differ in the camera and the eye?
STATION 8--Astigmatism
Look at the chart of radial lines. If you have glasses take them off. If you have contact lenses this may or may not work. Notice the intensity of the difference lines on the chart.
QUESTIONS:
1. Do the lines appear to be equal in intensity or vary in intensity? (This may be different for each member so please write what you see)
2. If some lines appear more bold than others you probably have astigmatism. What is astigmatism?
EXPLANATION OF OPTIC TOP
When the black and white pattern spins, subtle colors appear. They are called subjective colors because there is actually no color on the disk. Interference patterns on the spinning disk create and experience of color.
STATION 9 -- Near sighted vs far sighted
Place the lens in the holder hanging in the ring stand in the middle of the room so the laser's beam passes through it and projects on the wall. Have each member stand in front of the projection on the wall without glasses if glasses are worn. Move your head slowly to the left and to the right.
If the speckles move the opposite direction as your head movement you are near sighted.
If the speckles move in the same direction as your head movement you are far sighted.
If the speckles do no move you are neither far sighted or near sighted.
QUESTIONS
1. What were all your members?
2. What does farsighted and near sighted mean?
3. What type of lenses are necessary to correct the above conditions? Why?
STATION 10--Real eye
Name the parts labeled on the real eye. You may want to refer to drawing from station 7.
STATION 11--eye test
Stand on mark, 20 ft from eye chart. Cover one eye. Determine the lowest line each person in group can read. Look at chart to see what the person's eyesight is (left side of line). Repeat for other eye. Repeat for each member of group.
QUESTIONS:
1. What is each person's eye sight?
2. If 20/100 means you see at 20 ft what a normal person sees at 100 ft, how do you compare to a normal person? Do you have normal, better than normal, or worse than normal vision?
STATION 12--hearing test
Use a 500-100 cps(Hz) tuning fork.
Place the vibrating tuning fork's base on center top of persons head. Normal hearing = hears sound equally in both ears. Abnormal hearing = hears sound louder in one ear.
QUESTIONS:
1. What were your results for each person?
STATION 13--dB readingsweighting = C
response = fast
*** do this outside so there is less noise
Set sound meter range on 60. Softly say "Shh" into reading end of meter. What is the reading? (remeber the reading is 60 + whatever the needls shows)
Set the range on 70. Say "hello" softly. What is the reading?(now the reading is 70 + needle reading)
Set range on 80. Talk normally to another person. What is the reading?
Set range on 90. Whistle. What is the reading?
QUESTIONS:
1. Remembering that dB is a logarithmic scale (goes up by powers of ten for example goind from 10 to 30 is not a difference of 20 but a difference of 100(2 tens)), how do all your readings compare?