Recently, a high school Science Club generated a large number of questions involving temperature. Therefore, they decided to construct a thermal gradient apparatus in order to conduct a wide range of experiments beyond the standard "cookbook" labs. They felt that this apparatus could be especially useful in future ninth-grade biology classes, in which students must design and conduct individual, inquiry-based experiments as part of their training in scientific methodology. This article describes their experience building and testing a thermal gradient for laboratory use. (Contains 3 figures.)