NOTE TO TEACHERS:

These procedures are written to show you how you might use these technologies to teach science concepts. Suggested questions, approaches, and expected answers are all provided. Therefore, these activity descriptions should be used as a guide for your instructional planning, rather than as step-by-step directions for students.

Getting Started

How does the rate of evaporation of a drop of saltwater affect the resulting salt crystal formation?

The results may surprise you. In this activity you will be able actually to watch what happens as drops of saltwater evaporate at different rates!

Using the time-lapse photography software that comes with the QX3 digital microscope, you will capture a video of the evaporation of two different drops of saltwater.  One that evaporates quickly and one that evaporates slowly. 

For the "slow" evaporation, you can let a small drop of saltwater evaporate at room temperature.

The exact time needed for crystal formation depends somewhat on the climate of your classroom. [Teacher: Note that you should try this activity before using it with students to gauge evaporation time.] In drier climates crystals will take less time to form than in more humid climates (20 minutes or more). Evaporation time also depends on the size of the water drop. See tips for making smaller water drops in Procedure 2.

How can you make the second saltwater drop evaporate more quickly?

You can try using hot water for faster evaporation, but in many cases the drop of water cools to room temperature before it begins evaporating. As a result, you will see little difference in the crystals formed when compared to those formed from cooler saltwater. 

You will probably need to use a hair dryer or other warm air source to speed up evaporation. 

Procedure 1   |   2  |   3  |   4  |