Inquiry Skills Used

This is a scientific inquiry/investigation and possibly a technological problem-

solving activity.

Safety Considerations

Students should be wearing eye protection.

Background

The Italian scientist, Galileo Galilei, created one of the first thermometers in the late 1500s. It was a rather simple apparatus involving a long thin tube, open at one end, and a pan of water. Students can replicate this experiment, demonstrating the principle that air expands when heated.

What You Need

Eye protection

500 mL Florence flask (or boiling flask)

Test tube clamp or metal ring

Large beaker (400 mL)

Retort stand

Food colouring

Water

Bag of crushed ice or iced-gel pack

What to Do

  1. Fill the beaker half full with water coloured with the food colouring.
  2. Set up the Florence flask so that it is suspended either by the test tube clamp or by the metal ring, inverted, with the mouth of the flask in the beaker of coloured water.
  3. Place the bag of ice, or iced-gel pack on the Florence flask and have students observe what happens to the coloured water.
  4. Remove the ice, and then have students warm the flask with their hands. What do you observe now?

Where to Go from Here?

Have students find a way to calibrate this thermometer, so that you could use it as a thermometer. Compare the working of this open-air thermometer with a clinical thermometer or a weather thermometer. Is the principle the same? In what ways would Galileo's not be terribly practical? Would the results be different at different altitudes?

STSE Links

Bottles are never filled all the way to the top to prevent explosions. The air space at the top allows for contraction and expansion of the liquid with temperature changes. The opposite is applied when making jams and other preserves. As the containers are placed in boiling water without lids and heated to kill all the potential pathogens, everything expands. When the heat is turned off, the lids are quickly put on and as the preserves cool down, the lid also gets pulled down creating an excellent seal. The whoosh or pop you should hear when you open preserves, such as jam, is the outside air filling in the space left from the hot air contracting during cooling. If you don’t hear the pop or whoosh when you first open a new jar of jam, this may indicate that the seal was not good and the preserves may have gone bad.

Cross Curricular Connections

Language

  • The calibration process could be used as a writing opportunity for non-fiction procedural writing, giving instructions.
  • The history and stories of how much difficulty scientists had with measuring heat in the early 1700s makes for a fascinating read.
  • The Galileo Project at Rice University ( has a well-written account of science and technology at work involved in the development of the thermometer.

Credit Where Credit is Due

Suggested by an investigation in the Nelson 1997 series, Heat and Temperature, and an explanation and diagram in Scholastic's Everything You Need to Know about Science Homework.