611-2100 Density Rod: What floats in cold water, sinks in hot? Our precisely calibrated cylinder - that's what! It demonstrates the differing density of a liquid at different temperatures. Illustrated instructions. Consists of a durable hollow aluminum cylinder (6.5 cm long and 1.9 cm in diameter) that fits most graduated cylinders. Instructions with experiments. Good for middle school. Wt: 3 oz.

611-2105 Reverse Density Rod: Everyone knows water gets less dense as it gets warmer. Then why does this rod sink in cold yet float in less dense hot water? The answer lies in the fact that the density of the rod also changes with temperature. The rod becomes much less dense at higher temperatures. It wins the “race” against the heated water and floats, whereas the aluminum rod sinks.Contains: High-density polyethylene plastic rod, 1/2” in diameter, weighted and tested; instructions with theory.