What is meant by the phrase "form follows function?" Allow your budding biologists to discover first-hand through two activities. In the first, groups work together to discover whether a solid cylinder or an empty cylinder can support more weight, both directly and in relation to the weight of the cylinder. Once complete, learners examine an actual bone to determine whether it is solid or hollow, and what the advantages might be to the form of the bone. Note: while the publisher listed the lesson as being used for third grade through high school, it is most developmentally appropriate for upper-elementary or middle school. If using in high school, have the kids develop their own experiment to answer the question, "is a hollow cylinder or solid cylinder able to support more weight, relative to its own weight?"