Built around the question of how changing pressure affects an object’s position in water, this lab sheet walks students through a full scientific investigation using a clear plastic bottle, an eye dropper, modeling clay, and optional food coloring. Students write a hypothesis, follow a seven-step procedure, and record what happens at four distinct stages: bottle at rest, squeeze gently, squeeze harder, and release pressure. A labeled photo shows exactly how the dropper and clay weight sit inside the filled bottle, so setup is clear before the experiment begins. The explanation section on the sheet connects the observable sinking and floating directly to air compression, water displacement, and the buoyant force, making this a strong fit for grades 3-6 homeschool science.

The Cartesian diver experiment works as a standalone lesson or as an anchor activity inside a unit study on fluid dynamics or states of matter. Your student demonstrates understanding by completing the three-column results table, which asks not just what happened but why they think it happened, building the habit of evidence-based reasoning. Pairing this sheet with a lesson on Archimedes’ principle or Pascal’s law gives older students in grades 5-6 a concrete reference point for more abstract concepts.