Make Your Own Thermometer
Are you looking for fun hands-on science activities to teach your students about temperature? Have them make their very own thermometers by following these quick steps.
- 1 pint jar with cap
- 1 straw, preferably clear
- Some clay or play dough
- Rubbing alcohol
- Food Coloring
- 1 marker
- Fill the jar with equal parts water and rubbing alcohol about ¼ of the way up the jar
- Add a few drops of food coloring to color the temperature-sensitive liquid. Using red coloring best mimics a standard mercury thermometer.
- Secure the cap and shake well to mix the liquid and to ensure the food coloring is evenly dispersed.
- Punch a hole with a pen in the center of the cap, allowing the straw to feed through.
- Position the straw so that it dips into the liquid but does not touch the bottom of the jar.
- Use the modeling clay or play dough to wrap around the straw where it enters the cap to create an air tight seal.
- Use a marker to mark on the jar the water level in the straw at room temperature.
Liquid in Jar
Food coloring emphasizes the liquid level.
The hole should be sized closely to the straw.
Building the thermometer is only half the fun. Now experiment with your students by having them take their thermometers and place them in differently-heated places to watch what happens. Take it outside; place it in a shadow, in the sun light or wherever to see how temperature reacts with their thermometers.
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 students 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.