On Friday the students learned about crystals and crystal structures. We discussed unit cells and how atoms can be arranged within a crystal, and then discussed how these arrangements can lead to different electrical and optical properties.

The students’ first experiment was to analyze the crystals they started growing Monday. These crystals are piezoelectric, meaning that they produce a voltage when mechanical stress is applied. Therefore, the students were able to measure these voltages with potentiometers, and then also looked at their crystals under the microscope.

After, the students coated conductive glass with tungsten (VI) oxide to make “smart glass.” This glass changes color when an electrical potential is applied while it is in acidic solution. The scientists can try to conduct this experiment at home by connecting the positive terminal (red) of a 9V battery with an alligator clip to the graphite electrode, and the negative terminal (black to green alligator clip) onto the smart glass they made. They should place both the electrode and smart glass in a cup of lemon juice (or something more acidic) to observe the effect. Have the students try different acidic solutions to see which ones work!