The JumpStart Blog

Get on your sweater and start up that fire, because it is getting chilly as winter sweeps over us. To turn that nippy temperature into something fun the kids can learn from by making a simple homemade thermometer!

Materials:

• 1 pint jar with cap
• 1 straw, preferably clear
• Some clay or play dough
• Water
• Rubbing alcohol
• Food Coloring
• 1 marker

Instructions:

1. Fill the jar with equal parts water and rubbing alcohol about ¼ of the way up the jar.
   

   A little too much pouring.

2. Add a few drops of food coloring to color your temperature-sensitive liquid. Using red coloring best mimics a standard mercury thermometer.
   

   Food coloring emphasizes the liquid level.

3. Secure your cap and shake well to mix the liquid and to ensure the food coloring is evenly dispersed.
4. Punch a hole with a pen in the center of the cap, allowing the straw to feed through.
   

   The hole should be sized closely to the straw.

5. Position the straw so that it dips into the liquid but does not touch the bottom of the jar.
6. Use the modeling clay or play dough to wrap around the straw where it enters the cap to create an air tight seal.
7. Use a marker to mark on the jar the water level in the straw at room temperature.

Building the thermometer is only half the fun. Now go and experiment with your child by taking your thermometer and placing it in differently-heated places to watch what happens. Try the refrigerator; take it outside; place it in a shadow, in the sun light, or wherever to see how temperature reacts with your thermometer.

How does it work?
Liquids contract and expand depending on the temperature. Rubbing alcohol is more temperature-sensitive than water, so the liquid changes according to temperature quicker than using only water. When it is hotter, the liquid in the jar expands, pushing fluid up through the straw; the opposite is true for the cold.

This is also a good chance to educate your child on the Celsius and Fahrenheit temperature scales. Water freezes at 0 degrees Celsius and boils at 100 degrees Celsius. Fahrenheit, on the other hand, has water freezing at 32 degrees and boiling at 212 degrees.

It just goes to show that, no matter how cold it is outside, there is always fun and learning to be had!

Liked This Experiment?  Share It!

Filed under: Just for Fun! Tagged: | experiments, family activities, fighting boredom, science, Winter