Author Rob Dean previously published an Illuminations article concerning "challenge" questions that encourage students to think imaginatively with approximate quantities, reasonable assumptions, and uncertain information. This article has promoted some interesting discussion, which has prompted him to present further examples. Examples are presented from Dean's laboratory course, Scientific Methods in Biology, where students use either of two different methods to measure light-dependent photosynthetic events in isolated thylakoid vesicles. In making curriculum recommendations for programs in Molecular Biology and Biochemistry, the American Society for Biochemistry and Molecular Biology provided a list of skills that students should acquire during their undergraduate programs. Among these are "The ability to dissect a problem into its key features" and "The ability to think in an integrated manner." Questions such as those presented in this article provide students with practice in developing these important skills.