In order to learn more about Matter (solids, liquids, & gases) and the differences between liquids (density), we did a Liquid Layers experiment. You need: water, vegetable oil, shampoo, and syrup, plus a few items for the sink/float portion of the experiment.
Using a clear container, I poured in water first. We discussed what happens when oil and water mix. Next, goes in the oil, which settles on top of the water. Unlike another liquid, say milk, when mixed with water, oil and water do not mix. I even stir the two liquids to try to create a solution, but it just doesn't happen.