As part of our study of igneous rocks, the fourth-grade scientists have been busy learning about crystals and how they form. They began by growing a crystal garden in hands-on Science. In this experiment, students were required to follow a detailed procedure without assistance from the teachers. Over the next few weeks, the gardens changed daily as new crystals formed on the coal briquets from the solution the students had prepared. Through this experience, students learned that careful measuring and following each step of the procedure was important to successfully grow crystals.
Next, armed with the concepts of control and variable, as well as their own powers of observation, the fourth-graders set themselves to the task of identifying an unknown household crystal. They were given four known crystals and were told that the unknown crystal was related to one of these known crystals. Next, they performed various tests on the known and unknown crystals as they tried to find similarities and differences among them. They observed the shapes of the crystals with microscopes and magnifying glasses, they crushed the crystals to observe how they behaved, and they will continue this coming Friday by dissolving the crystals in water to observe any differences in this property. Throughout the process, they are learning about the crucial concepts of control and variable, and the ways that uncontrolled variables can sometimes interfere with experiments.