I like the concept but some of the answers can be really misleading.

Can be carried, is found in classrooms, not made of plastic, and inexpensive. None of that points towards a microwave for me. Microwaves CAN be carried I guess, but who has microwaves in classrooms? My microwave has plastic cowling on the front, and microwaves are like 70-100 bucks the last time I checked. Some of that is on me for the phrasing (does it contain plastic I guess should have been used, as an example) but it’s a bit odd.