Put the strips in the cup (or attach them to the thermometer) along with the thermometer. Add just enough cool water to cover the bulb of the thermometer. Both thermal sensing strips will be black.

Now squirt in some warm water, watching for the first hint of color on the thermal sensing strips. Stir with the thermometer.

When one of the strips begins to show a color, record the temperature on the table below. Thereafter, add the warm water slowly, so not to miss anything.

The liquid crystal temperature sensing sheet uses organic materials that are slightly sensitive to air, water, heat, and age -- so the temperature scale can drift a bit with time. You may also have noticed that the color depends a bit on who is looking, and from what angle. Color blind people will see the colors in still a different way. The calibration is specific to your sample, and to the way you calibrated it. There is no right answer here, except that once you have calibrated the liquid crystal your way, you should get consistent results.

Using the liquid crystal sheet to measure the temperature is the hard way to do it; but it is a very good way to show how temperature varies from place to place. We can tell at a glance what would take many measurements with a single thermometer. The important thing you have learned from the calibration is how sensitive it is: whether "green" differs from "brown" by one degree, ten degrees, or one hundred degrees.

Check the box when you are done:  

Next activity: Science content: What we can learn about temperature and thermal energy using the thermal sensing sheet