Crystals we see everyday are table salt, sugar, ice, snow, quartz and diamond. A crystal is formed by an arrangement of atoms, molecules, or ions. Because of the repeated units, crystals have recognizable structures.
The real fun is in seeing crystals form. Salt, sugar, borax and alum make the best crystals, but there are safety factors to be recognized. Small children will often put things in their mouth and swallow them. These activities are to be monitored by an adult at all times.
This year borax had the best result for our science classroom. It dissolved quickly and the crystals started growing as soon as the solution cooled.
A pencil with attached string and paper clip
Food coloring (optional)
Bring a pot of water to a boil and pour into the jar. This is a job for an adult! Add 3 tablespoons of borax per each cup of water and stir. Everyone gets a turn stirring. It’s alright if some borax settles to the bottom of the jar. If you want colored crystals, stir in some food coloring.
Balance the pencil across the jar mouth so the string and paper clip are suspended in the middle of the jar. Keep the jar somewhere where it is safe from being disturbed, but is easily viewed. Monitor it carefully until the solution is cooled. Chart results by the hour. Have children write about their discoveries in their journals.
So, what did we do and why is it science? When the borax is in with the water, a suspension is created. A suspension is a mixture that contains solid particles large enough to settle out. By mixing the borax into hot water, instead of room temperature or cold water, the borax stays suspended longer within the water. As the borax begins to settle out, or sediment, it begins to crystallize. The crystals cling to the string and to the sides of the jar as well as the bottom. The borax continues to sediment on the string and you have crystals!