A thermometer is an instrument that measures the temperature inside or outside. Thermo means "heat" and meter means "to measure." Most thermometers are filled with mercury or colored alcohol. When it is hot, the liquid inside the thermometer expands. Since it is encased in a plastic or glass tube, the liquid can only go up. When it is cold, it constricts, and goes back down. Fourth graders usually learn about weather and measurement in school. Making a thermometer at home or in the classroom reinforces concepts fourth graders are exploring. While a homemade thermometer can't measure degrees like a calibrated store-bought one can, children can still see how a thermometer works by building their own.
- Clear 11-ounce plastic bottle
- Tap water
- Rubbing alcohol
- Food coloring
- Clear drinking straw
- Modeling clay
Show More
Instructions
-
-
1
Fill one-fourth of the bottle with equal parts of water and rubbing alcohol.
-
2
Add food coloring drops to the liquid and stir the mixture with the straw.
-
-
3
Put the straw into the liquid, but don't let it touch the bottom of the bottle.
-
4
Hold the straw in place and seal it to the top of the bottle with the modeling clay.
-
5
Put hands on the bottle or set it in a sunny window sill. The heat from a child's hands or the sun will make the liquid in the bottle expand and rise up the straw. If the liquid gets hot enough, the water and alcohol mixture will overflow from the top of the straw.