Sketching plays an important role in learning in the sciences. The process of sketching can help students think about and better understand scientific concepts. By sketching collaboratively, students can also compare their mental models with each other and share them with instructors in order to further enhance their understanding. What if these sketches could come to life so that students could experimentally test out and iteratively refine their models of natural phenomena and systems? We are designing SciSketch, a tabletop tool for sketch-based problem-driven collaborative learning in the sciences. The system tracks multiple pen inputs on a tabletop display surface and can transmit sketch data to a remote computer. The first prototype provides basic functionality of digital sketching tools, such as copy, paste, and playback. We study how such a tool could be incorporated into the classroom environment for undergraduate courses in biomedical engineering.