Add ¼ cup of Epsom salts to ½ cup of boiling water. Stir until all of the salt is dissolved. Add more salt, ½ teaspoon at a time until no more salt will dissolve. Pour just enough of the mixture into a shallow container to cover the bottom. Set the container in a sunny place where it will not be bumped or moved. As the solution cools, crystals will form. Compare the shape of the new crystals to the shape of the original Epsom salts. Experiment with pouring the solution over a sponge or adding food coloring to the solution.
Make the salt solution from activity one, multiplying it by six. Fill two pint jars about ¾ full with the solution. Place the jars on a cookie sheet or tray. Tie a washer on each end of a one-inch wide strip of cotton about 18-inches long. Drop one washer into one jar and the other washer into the other jar. Position the jars so that the strip hangs two inches above the tray. The strip will absorb the solution, and it will drip onto the tray. If undisturbed, the remaining salt will build stalactites and stalagmites as the water evaporates.
Investigate how different substances make different shaped crystals. Make crystals from Epsom salts as described in activity one. Then repeat the procedure two more times. The first time, replace the Epsom salts with regular table salt. The second time replace it with sugar. Watch as the crystals form and compare the shapes made by the different solutions. Then use a magnifying glass to compare the growing crystals to the original salt or sugar. Finally, look at pictures of actual crystals from different minerals and compare them to the newly-made crystals.
Find four places with widely differing temperatures--for example, the freezer, refrigerator, countertop, and a sunny windowsill. Prepare the salt solution from activity one, multiplying it four times. Divide the solution evenly into four shallow containers, just covering the bottom of each. Place each container in one of the four places. Periodically check the crystals in each place to see how they are growing, but do not move or bump them. At the end of three days, remove the crystals from their places and compare them. Observe and draw conclusions regarding how temperature affected the crystal growth.