A thermometer measures temperature and can be made quite easily. First, you need a jar or plastic bottle to hold the liquid. In the cap or lid, make a hole small enough for a straw to pass through. Next, mix equal parts of water and rubbing alcohol, dye it with food coloring, then fill the container 1/4 of the way full. The colored water will clearly allow you to see the changes in temperature. Last, insert a straw through the hole, but don’t allow it to touch the bottom. Now all you need to do is test your thermometer in different temperatures.