What Would You Do Without Your Thumb

What would you do without your thumb?

Shannon Souaibou

Materials:

A few rolls of masking tape

Students and their hands

Time needed:

10-20 minutes or more depending on how much discussion takes place

When can I use this?

-When discussing the skeletal system and joints

-Evolution of opposable thumbs-why did a saddle joint evolve, why is it needed, what organisms have saddle joint-to get them thinking about why new characteristics develop

**If you think of any other way this can be used please let me know***

Procedure:

-Each student should take a long piece of masking tape, but not too much

-With the tape, attach your thumb to your index finger on your dominant hand

-Now try to complete various daily activities with your thumb taped to your index finger

-Some suggested activities:

-Write your name

-Open a doorknob

-Turn the pages in your textbook

-Tie your shoe

-Unbutton a shirt button

-Unzip a zipper-not on your pants please!

-Pick up a penny or other type of coin

-Turn on the water faucet

-What activity can you think of that is more difficult without your thumb?

-Give them some time to try these activities

-What else can you do?

-Have them tape their thumb on their non-dominant hand as well, they can either release the dominant hand from being taped or try it with both thumbs taped

-Challenge students to spend the rest of the day with their thumb on their non-dominant hand taped (Hopefully using the non-dominant hand will not interfere too much with their other classes and you won’t receive complaints from other teachers)

-Once you have had enough with the activity, ask the students to stop and discuss what they noticed, you can ask them about the advantages of having a saddle joint, how is it helpful, is there anything negative about having a saddle joint, why did the saddle joint evolve, when do you think it evolved

Some Information:

-A saddle joint allows for back and forth and side to side motion but limited rotation

-The bones have both concave and convex places at the joint.

-A saddle joint has two saddle-shaped surfaces at right angles to each other.

-Our thumb is called opposable because we can touch every finger on our hand with the thumb

-Most primates, pandas and some marsupials are known for having opposable thumbs or toes

-Some believe the saddle joint and opposable thumb evolved with the use of tools to make it easier to hold tools

This diagram shows the saddle joint at the base of the thumb and an example of what that bones resemble at the joint