A thermometer is an instrument that measures the temperature. Depending on what country you live in, temperature is measured either in a scale called Fahrenheit or Celsius (sometimes called Centigrade). There are thermometers for food, humans, and the weather. You can even make a thermometer yourself, it's simple.

Here's what you'll need:
-Water (plain old tap water will do just fine for this experiment.)
- Rubbing alcohol
-1 clear plastic bottle with a narrow neck
-Food coloring in your choice of color
-See-through plastic drinking straw
-Modeling clay.

Pour equal parts of the water and alcohol and a couple of drops of food coloring into the bottle (the liquid should only fill up about a quarter of the bottle.) and give it a shake to mix. Drop the straw into the bottle (it should touch the bottom) and plug the opening with the clay. That's all there is to it. Now it's time to make sure your thermometer works. What happens when you place it in direct sunlight and the liquid becomes warmer? If your thermometer works properly, the colored liquid will rise up through the straw. In fact, if the liquid were to become extremely hot, the liquid would most likely come out the top of the straw.

Bring your thermometer outside with you, how does the colored water react inside the straw? Does it go up or down? Run it under warm water and then cold, the colored water will react accordingly. Of course this isn't an accurate measure of water temperature, and there's no way of telling how hot or cold the water actually is, but this should give you some idea of how a thermometer works.

Making a thermometer is a great rainy day craft for kids. It's easy, quick and in most cases involves items found around the house. Why not make it your next project?