Grandparents and Special Friends Day in the Lab

On Wednesday, Nov. 24, 2010, the Lower School Science Lab was full of activity as the 4th grade students and their grandparents and special friends visited for a very special hands-on, inquiry-based lab. The children and adults investigated the principles of buoyancy and density by making their own Cartesian divers. The diver is named after a French scientist and philosopher, Rene Descartes. The traditional Cartesian divers have been made out of glass medicine droppers or delicate glass ampules. The students used safe, plastic medicine droppers, or pipettes, weighted with a metal hex nut. When the students and grandparents properly adjusted the buoyancy, the diver would sink when pressure was applied to the outside of a 1 liter bottle, and would float when that pressure was released. The students noticed that the water level and air pocket size inside the diver changed when pressure was applied and released. Using the formula Density=Mass/Volume, the students could state that as more water entered the pipette, the mass changed, and the diver became less buoyant and sank. Then students realized that when the pressure outside the bottle was released, the compressed air inside the diver expanded (took up more space), and pushed some of the water back out. As the water level dropped inside the diver, it became more buoyant and floated to the top.

At the end of the lab, the students and grandparents/special friends were asked this question, "What would happen if we sealed the end of the diver with a drop of glue so no water could enter or leave the pipette? Would the diver still work?" I hope everyone puzzled over this during the Thanksgiving break. Maybe someone gave it a try while they were resting from eating all that turkey!

"How do you know what an owl eats if we can't see the owl hunt?" This question was posed to the 4th graders today as they began their investigation of the "owl pellet". The pellet is formed from the undigestible materials of the owl's prey, like bones, fur, and even feathers. The owl regurgitates this undigestible material in the form of a pellet. When the lab is completed, the students will be able to describe the food web that has the owl as its "apex predator". Students will also be constructing a skeleton of one of the owl's prey from the bones collected during the lab.

The 4th graders had an enjoyable morning at Discovery World in downtown Milwaukee on Wed. Nov. 3rd. They had a "Behind-the-Scenes" tour where they got a chance to see the aquariums from the other side, and learn how Discovery World manages to care for so many fish. They also had a chance to go aboard the "Challenge", a replica of a Great Lakes schooner and see how sailors lived and worked aboard ship. The students also saw and explored a much larger model of the Great Lakes. They finished their visit with a lab in which they learned about the water cycle, ground water, and aquifers.