The multistep nature of tumorigenesis is a foundational concept in the context of Cancer Biology. Many students do not appreciate the complex nature of cancer development nor do they understand how scientists are able to unravel the molecular pathways that lead to tumorigenesis. In this small group activity, students are presented with background information about the multistep nature of tumorigenesis and complete a priming activity that allows them to brainstorm and discuss experimental design. Students are then presented with data from the landmark manuscript, published in 1998 by Vogelstein et al., describing the first pathway of genetic alterations associated with colorectal tumor development. Using selected pieces of the manuscript, students answer discussion questions and analyze the data presented in the paper. Using their analysis, students are able to create a scientifically valid molecular model of colorectal development that matches the model presented in the literature. The group activity can be followed by a whole class discussion about current knowledge about colorectal tumor development.