Kindergarten scientists built upon previous investigations with density to hypothesize which objects would sink and which would float. Loved listening to the scientific chatter as lab partners sorted the objects and made hypotheses before placing those objects in the water. Some of our findings surprised us! Click here to find out more. This is a fun investigation to do in the bathtub or sink.
Then I asked what would happen if I placed an object that sank on top of one that floated? Hmmm…. I also demonstrated that the plastic knife could float if you placed it carefully in the water lengthwise. Surface tension holds it up. So, maybe the shape of an object also impacts whether it will sink or float. We are beginning to explore buoyancy.
Will rocks float? We discovered that pumice, a volcanic rock, floats. Love turning their thinking upside down!
Epsom salt which is also known as magnesium sulfate is actually not salt. It’s a chemical compound made up of magnesium, sulfur, and oxygen. In this simple investigation, third grade geologists used Epsom salt and hot water to make crystal sun catchers in Petri dishes. This is a simple project to try at home!
Heat 1 cup of water to boiling (212 degrees F or 100 degrees C). I used my electric tea kettle. Add 1/2 cup of Epsom salt. Stir until it dissolves and your solution is saturated. (We doubled this.) Pour into a shallow plastic or glass dish.
The term saturated solution is used in chemistry to define a solution in which no more solute can be dissolved in the solvent.
After the water evaporates, crystals appear. “Crystals are a special kind of solid material where the molecules fit together in a pattern that keeps repeating itself. Because of these patterns, crystals from all sorts of unique shapes.” (Ducksters)