Some interesting ways to use crystals in a science project are to collect and group them, make a model of crystal lattices or the molecular structure of the crystal, grow crystals or prevent crystal growth. Students can also grow crystals to make rock candy.
To make crystal or rock candy, the student dips wooden skewers in water and then rolls the wet ends into white sugar. As they dry, he dissolves 1/2 cup of white sugar in 1 cup of water, stirring constantly. He continues to do this until no more sugar can possibly dissolve because the water is completely saturated with the crystals. Then, he heats the sugar water to a boil and turns the heat down to a simmer for five minutes until the remaining sugar in the pan dissolves and the liquid turns clear.
Once the sugar water cools down, the student pours it into jars and mixes it with food coloring if desired. He places the prepared sticks in the solution and waits for a week for the crystals to grow. The student can also do this project using Borax for non-edible crystal growth.
The student can opt to collect crystals and arrange them according a grouping method. Some crystals that can be used are salt crystals, sugar crystals, quarts and even snowflakes.