Thermometer

= Make a Thermometer =

|| || 1. Remove the jar's label. 2. Remove the top from the jar make a small hole (just big enough so the straw can fit in).
 * **Materials**
 * Rubbing Alcohol
 * Water
 * Cylinder shaped clear jar or bottle (bottles with a narrow neck work best)
 * 1 straw
 * Modeling clay
 * Food coloring
 * Procedure**

3. Pour equal amounts of cold water and rubbing alcohol into the jar/bottle, filling it to about 1/4 of the container.

4. Add two - three drops of food coloring. 5. Close the bottle and make a small hole in the lid (just big enough to insert the straw).

6. Place the straw in the jar/bottle so that the bottom of the straw is submerged in the liquid but not touching the bottom of the container. 7. Seal the top of the bottle with the modeling clay so that it has a tight seal and so the straw stands upright.

**How Does it Work?** Test your thermometer. Grasp the jar/bottle with your hands and hold on for 5 five minutes. What happens Describe to the best of your ability how this device actually measures air pressure. Include the following terms in your description: pressure, expansion, contraction, density.
 * 1) Place your thermometer in a pan of cold water. What happens?
 * 2) Place your thermometer in a pan of hot water. What happens?

What can you do to improve the functioning of this device? Can you improve the accuracy? Precision? Can you make the device more stable or portable? You may select any materials we have here today or suggest alternative materials. Be clear in your description as to why these modifications will improve this device.
 * Engineering Experience: Ideas for Improving the Design**