To grow salt crystals, you will need water, Epsom salt, a clean jar and a small piece of cardboard. Mix 1/2 cup of Epsom salt with 1/2 cup of water. Boil the solution for only a few seconds, then place the small piece of cardboard in the solution. Crystals will begin forming on the cardboard in a few hours to a couple of days.
Growing alum crystals calls for water, alum powder, cotton thread, two clean jars, a pencil and a coffee filter. Stir 2 1/2 tbsp. of alum powder into 1/2 cup of hot--not boiling--water in one of the clean jars. Cover the jar with the coffee filter and allow the solution to sit overnight. The next day, pour the solution into the second jar, removing any crystals that have formed at the bottom.
Tie the biggest crystal to the end of the cotton string and tie the other end of the string to the middle of the pencil. Suspend the crystal in the solution from the pencil and cover the jar with the coffee filter. Allow this to sit for several days while the crystals grow. Every day, remove any crystals that have formed at the bottom of the jar, since these will hinder the growth of the crystal on the string.
Rock candy is basically a large, edible collection of sugar crystals. The recipe calls for water, sugar, a clean jar, a piece of cotton string, a galvanized washer, a pencil and waxed paper. Boil 2 cups of water and dissolve 4 cups of sugar in the water by stirring with a wooden spoon until the solution is clear. Pour the solution into the jar.
Tie the washer to the end of the string, and the other end of the string should be tied to the middle of the pencil. Dip the washer into the solution, then place the string on a piece of waxed paper for three days to allow it to dry, covering the solution. After the string has dried, place it back into the solution, suspended from the pencil, and cover it. Allow this to sit for seven days. The rock candy should then be big enough to eat.
Parental supervision is recommended for crystal growing. You can find the ingredients at the grocery store. Patience is also required, since most crystals take days to grow. Try growing them under different conditions to see what effect those conditions may have.