This part of the session presents two different methods for determining the actual relationships between the volumes. If you're using manipulatives, it is important to be very careful to make sure the heights and diameters of the cylinder, sphere, and cone are congruent. Sometimes when the clay sphere is flattened into the cylinder, there are holes and gaps, so it appears that the volume of the sphere is greater than it really is.
Furthermore, when forming a cone shape that fits into the cylinder, use stiff paper that doesn't have a lot of give to it. Otherwise, you may again have inaccuracies in the relationship between solids.
It may be easier to observe the relationships between volume using plastic cylinders, cones, and spheres, as mentioned in the Alternate Experiment. Use water to fill the solids (color it with a drop or two of vegetable food coloring).
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