It is very important that children are exposed to chemistry at a young age. That being said; there are many fun, easy, and safe projects that can be conducted with children as young as 5 years old.
As a child, I can still remember "growing my own crystals" in my basement at home. Although growing crystals is a slow and boring process, the results are very exciting once they turn out! The shape of the crystal once it is fully developed reflects the patterns by which the molecules of the crystal build up.
In order to grow your own sugar crystals (AKA rock candy) at home, all you have to do is follow these simple directions. First, you start with a sugar solution that has as much sugar dissolve in it as possible. Because there is an excess of sugar in it, the water evaporates from the solution, leaving the sugar to be forced to leave the solution and become a solid again. As the sugar leaves the water and forms into a crystal, the crystal becomes suspended into the water solution. The more water that evaporates from the solution, the more the crystal grows! Depending on how slow the crystal grows, it may take on different shapes as it grows. The shape of the final product will reflect how slowly or fast the crystal grew.
To make the saturated solution needed to grow your crystals, there are many different substances you can use that will make the project work. You can use: sugar (to form the sugar crystals or "rock candy"), salt (sodium chloride), alum (aluminum ammonium sulfate), copper sulfate, Rochelle salt (potassium sodium tartrate), or potassium ferricyanide. These different substances will form into different shapes of crystals because of their different chemical makeup.
Now that the process of growing crystals has been clarified, let's recap and put into shorter terms what has been said. You first have to make a saturated solution, which is what the water evaporates from to form the crystal. You then have to wait for time to pass by as the crystal grows and forms its shape. This process may take a while, but a calm and steady environment will speed up the process. If you disturb the crystal, the process will go slower.
There is no limit to how big your crystals can be. Being that most students have to complete a chemistry course in high school before they graduate, it will only get them a head start by conducting chemistry experiments at a young age. So, by following these instructions, you can build your own crystals at home in no time! (Ok they actually do take some time)