Students have individual assignment to do a rough calculation related to their project (or course or larger activity, etc). Emphasizes the need to do rough approximate calculations, making assumptions where needed. I have given students a few days to do it, but when I presented this at the 2010 Capstone Conference someone suggested it could also be done with a very short (10 minute) turnaround. I use it to get students diving into the technical depth of their projects early on, before they fully know the territory - but it could be used in other ways too. Main thing is that it is actually done on the *back of an envelope* - this constrains how much the students can write and also adds some humor.
Other Info
Audience: any - could be a whole course, could be a team on a project. Works across all years.
Strengths
Applicable to many courses & contexts.
Teaches students about the process and value of completing rough calculations/estimates.
Forces students to deal with unknowns and make assumptions.
Weaknesses
Needs some structuring to identify an appropriate back-of-the-envelope calculation. More advanced students can often identify and frame these themselves; other students may need more assistance.
Variants
Could be done over a period of a few days or as a 5-15 minute assignment in class or in a team meeting.
Could do a pre-activity with teams or a whole class to brainstorm possible back-of-the-envelope calculations that apply to their project or the current course material. Then can divide up that list, assigning different calculations to different people.
Can return to the back-of-the-envelope calculations throughout the class; can also refer to the concept of BotE in the context of new calculations and students will better understand having done an initial one.