The problem scenario: A child in Toms River, NJ develops leukemia. Citizens in the town begin to notice what seems to be a high incidence of childhood cancers. They think they have a cancer cluster and suspect that a local chemical manufacturing plant and an illegal toxic waste dump are to blame. In problem Part 1, students learn about the biology of cancer and its connection to DNA structure and function as they encounter the true story of the Anderson family. In Part 2, they are introduced to the town of Toms River, and begin to make evidence-inference-explanation connections between local factors and a high incidence of childhood cancers. In Part 3, students critically examine the evidence for existence of a Toms River cancer cluster and its possible connection to environmental toxins from specific EPA sites, a local chemical manufacturing plant, and an illegal dumping site.