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Sensitivity Tester

Sent in by:
Sarah of Brookline, MA

It's up to you: one point or two?

## Materials Needed

• 12 paper clips
• 8 index cards
• pen and paper for charting
• large pieces of paper for mapping
• markers or crayons
• a friend

## Instructions

1. Can you feel what you can see? To find out if you can, make 8 different cards to test your sensitivity.
2. Unbend 12 paperclips and tape them to index cards making sure that the unbent point sticks out at least 1/2" over the edge of the card.
3. Make four cards with just one paperclip and four cards spacing two paper clips apart by 1/2 centimeter, one centimeter, two centimeters and three centimeters. (You will have a total of 8 cards.)

1. Draw a chart for recording your results. In separate rows along the left side of your paper, write "upper arm", "forearm", "palm", and "fingertips". Across the top of your paper make two columns for each person. Above the left column for each person write the name and "right". Above the right column for each person write the name and "wrong".
2. Before you begin testing, predict where you'll be the most sensitive and why.
4. Guess whether the card has one or two points.
5. Your friend records whether each guess is either right or wrong. He should also stack the cards in a right and a wrong pile.
6. After you're done testing one area of the arm compare the right and wrong piles of cards. Do you see a pattern?
7. Try testing on your fingertips, palms, forearms and upper arms to see which parts of your arms are the most sensitive. Be sure to mix up the order of the cards before you test each part of the arm.
8. When your arm is done, switch roles and test your friend's arm.
9. Then, compare your results. Which part of your arm felt more sensitive to touch while you were doing the experiment? Does this match your predictions? Were you both more sensitive in the same parts of your arms?
10. Use your data to draw a map to make it easier to see which parts of your arm are more sensitive than others.
11. Trace around your arm to make the outline for your map.
12. Then use the number of right answers you got for each part of the arm as the basis for how sensitive they are.
13. Decide which colors will represent which levels of sensitivity and then color your map accordingly.

Here's the sci scoop on why parts of your arm are more and less sensitive than other parts. Our skin has nerve endings that let our brains know when something is touching us. The paper clip points push on our skin and start a message going along the nerves to our brains. Some parts of our bodies have more nerve endings than others. Our upper arms don't have many nerve endings so when two points hit, they might only be hitting one nerve ending. So your brain thinks there's only one point. Our fingertips have lots of nerve endings. When two points hit, your brain gets two messages and thinks there's two points. When the points are farther apart, it's easier to hit two nerves. When they're close together, it's harder.

Dawson, age 9 of Miles, IA wrote:
We tested our Upper Arm, Forearm, Palm, and Fingertips. My most sensitive spot was my palm. the experiment was AWESOME!

Liam, age 10 of Miles, IA wrote:
In my upper arm I could not really feel them but in my palm and finger tips I was a lot more sensitive.

Logan, age 9 of Sabula, IA wrote:
My palm has the best feeling and my forearm is the worst.

Ginny, age 9 of Sabula, IA wrote:
My palm is more sensitive.

Sabrina, age 10 of Sabula, IA wrote:
I got more right on my finger tips than eney other one palm and upper arem has 3 fear arm has 4.

Keysha, age 10 of Sabula, IA wrote:
My most sensitive parts that we tested were my forearm and palm, they tied at 7 out of 8 tries correctly. My friend Bryn and I tested four parts of our bodies. We tested our upper arms, forearms, palms, and our fingertips. I thought that my fingertips would be the most sensitive because they are smaller than the other parts tested. My upper arm came in next with only two answers wrong. My fingertips actually were the most insensitive.

Noah, age 9 of Sabula, IA wrote:
We tested upper Arm, forearm, palm, and fingertips. My fingertips where most sensitive.

Valicia, age 10 of Sabula, IA wrote:
On my upper arm I had 5 right and 3 wrong. On my forearm I got 4 right and 4 wrong. On my palm I had 7 right and 1 wrong. On my fingertips I got 5 right and 3 wrong. Total 21 right and 11 wrong, we did 32 all together.

Josie, age 10 of Miles, IA wrote:
I loved doing this tester. I was most sensitive in my fingertips. I got 7 right and 1 wrong. I thought I would be most sensitive in my palm but I wasn't! I was very surprised. I would highly recommend this tester because it's so much fun.

Alix, age 11 of Miles, IA wrote:
When I did this I got all of them right on my finger tips, but the others I got wrong. But I think it was the best. I think my class had lots of fun doing this I thought it was the best I have ever done.

Evan, age 10 of Miles, IA wrote:
When I did it my forearm was my most sensitive spot I got all of them right. my least was my fingertips I got three wrong. I had fun doing the experiment.

Jacques, age 10 of Sabula, IA wrote:
My most sensitive spot was my palm I got seven right and one wrong and my least was my fore arm I got four right and four wrong.

Katelynnn, age 11 of Sabula, IA wrote:
My partner and I found out that his most sensitive spot is his upper arm. And we found that my most sensitive spots are my finger tips and upper arm.

Hally, age 10 of Sabula, IA wrote:
My partner and I tested each other for our upper arm, fore arm, palm, and wrist. My most sensitive spot was my fore arm. My partner's most sensitive spots were his upper arm and his fore arm. I got quite a few wrong on all the others. Some times I didn't know.

Evan, age 10 of Miles, IA wrote:
My most sensitive spot was my fingertips and I only missed 1. The less sensitive spot was my palm, forearm and upper arm. My partner was more sensitive in the palm.

Edwin, age 10 of Sabula, IA wrote:
My fingertips were my most sensitive spot. And my less sensitive spot is my upper arm. I got 7 right and 1 wrong for my fingertips. I got 5 right and 3 wrong for my upper arm.

Savannah, age 10 of Sabula, IA wrote:
My upper arm and fingertips was the most sensitive because I could feel they the most. than of mine palm and fore arm because I got 7 right and 1 wrong on mine upper arm and fingertips on my palm I got 4 right and 4 wrong 6 right and 2 wrong on mine forearm.

Justice, age 10 of Miles, IA wrote:
My partner and I tested our upper arm, forearm, palm, and fingertips. My most sensitive spot was my fingertips. I got 5 right and 3 wrong. My partner's most sensitive spot was his palm. We had fun doing the project I hope to do more projects during the year

Jayden, age 10 of Sabula, IA wrote:
The most sensitive spot on my arm was my palm and fingertips. My least sensitive spot on my arm was my upper arm and forearm.

Bryn, age 10 of Sabula, IA wrote:
My fingertips were the most sensitive. My forearm was the least sensitive spot. Keysha was my partner her most sensitive spot was her palm and her forearm tied. I loved this activity it was really fun!!!

Grace, age 10 of Miles, IA wrote:
My partner Logan and I had tested our upper arm, forearm, palm and fingertips. I was most sensitive in my fingertips and my palm I didn't miss any. Logan did is more sensitive in his forearm.

Cierra, age 10 of Sabula, IA wrote:
I did part of the experiment. The upper arm was my most sensitive spot.

Morgan, age 10 of Miles, IA wrote:
My most sensitive spot is my palm, and fingertips. My least sensitive is my upper arm, and fore arm. I think this was a great fun project. Thanks to both of my teachers.

Bryce, age 10 of Miles, IA wrote:
When I did the experiment I had fun. My most sensitive spot was my fingertips I got them all right and I missed 3 on my upper arm and I got 5 right. I also missed 3 on my forearm and I got 5 right again. On my palm I got 7 right and 1 wrong on my palm.

Cora and Byrce, age 10 of Miles, IA wrote:
When my partner Byrce poked me. My most sensitive part were my fingers and Byrce's was his fingers too! We did upper arm, forearm, palm, and fingertips. On both of us our least sensitive spots were upper arm and forearm that were tied.

Brock, age 11 of Miles, IA wrote:
My partner and I tested it and my most sensitive spot was my forearm and my upper arm. My partner's most sensitive spot was her forearm.

Hunter, age 10 of Sabula, IA wrote:
On my sensitivity test I got the most on my palm I got 6 out of 8. On our sensitivity test we did the palm, fingertips, forearm and upper arm we had fun.

Etienne, age 11 of Winter Haven, FL wrote:
the paper clips have diffrent spaces in between. they dont have the same values of there centimeter, so I know that the index cards can be alot of diffrents of mesur.

Alexa, age 9 of Gaithersburg, MD wrote:
I tested my head with my friend Hannah. We did forehead, cheeks, nose and chin. My most sensitive spot was my chin. I got them all right. I missed 1 on my forehead, 2 on my cheeks and 3 on my nose. Hannah's most sensitive spot was her nose. She got them all right. She got 1 wrong on her forehead, and her cheeks and chin tied with her missing two.

not yet implemented