As part of a larger solution to the problem of diagram assessment in online education, this paper explores how to allow students to "show their work" in the creation of a sketch, the same way they might show their work on, say, a math problem. We propose a Snapshot feature as an extension to our web-based Sketch Tool. This feature allows students to capture individual steps of sketch creation and then play them back. Instructors then have more information with which to assess student knowledge. Additionally, this paves the way for automated assessment--instead of a software tool having to go through every sketch and try to determine the relevant ones, it can focus on the steps students have labeled as important. Students could also use the feature as a rudimentary animation tool, or work collaboratively by adding on to other students? Snapshot sequences.