I live four blocks from school. When I have a couple of free hours and I am tired of reading (rarely!), I run down to school to work for a couple of hours. Yesterday, I worked on a place to put the schedule for the three new preps I am teaching next year. (Washi tape and letters taped with double-sided tape to the non-magnetic board. With a magnetic board, I use the same tape but then the adhesive-backed magnets for the letters.)
Maybe a bigger problem than students asking that question was that after I answered it 10 times, my smart mouth would start making up "creative" answers: swinging from the lights, nothing, just looking at each other, taking naps, coloring, etc.