We experimented with the viscosity (thickness) of three different liquids: Honey (the thickest), water (medium), and oil (the thinnest).
First, we set-up two containers. In one, we poured the honey in first, then the water, then the oil. In the other, we poured the oil in first, then the water, then the honey. In both containers, the honey sank to the bottom, the oil rose to the top, and the water sat in the middle.
Then we experimented with dropping various treasures into our containers, observing that some of the treasures were heavy enough to sink through the oil, water, and honey, while others sunk through the oil and water, but floated on top of the honey, while others were light enough to float on top of the oil. So neat!