Instrument DIY classroom: homemade improvised thermometer

Soda finished, don't throw away the bottle and straw, they can also be used as a thermometer. Of course you need to prepare a pen, a ruler, silly putty, red pigment and water, a refrigerator is also an essential one, producing method note's half a bottle of water in the bottle, and put some red pigment, make water into red. Use a ruler, every 1 cm on the straw painting a mark. Insert a straw soda bottle, then sealed the bottle with silly putty, and no leakage. In this way, homemade thermometer is ready. Second, experimental methods can now put the homemade thermometer under the sun, write down the water level in straw; And then in the refrigerator, No less than 4 degrees Celsius) The water level, write down a straw. Compare red water of straw, straw found in the water column in the environment of the higher temperature will rise and fall in low temperature environment. Three, to explore the cause of the water column lifting the air is heated in the soda bottle, pumping water into the straw, the water will rise; Bottle of air encounter cold contraction, straws in the water column will drop. So, homemade water thermometer can lift with the change of environmental temperature.