This morning mrdardy dropped by:
This is one of my all-time favorite problems. I usually set this up with 500 lockers. This kind of forces students to use the important problem-solving principle of reducing a complex problem to a much simpler one. Students typically offer 10, 15 or 20 lockers as a manageable set that they can actually simulate by hand. I have used this problem with Geometry kids, Algebra II kids and with Precalcuus kids and it is always an interesting conversation.
I had planned to give Geometry the locker problem today and took his suggestion of upping the number of initial lockers to 500.
However, geometry wasn’t too happy with me today; yesterday I handed out four lunch detentions and ripped into a couple kids. The word spread and they kind of had a mini revolt of taking an extreme and not talking at all. I talked to them about how they are honors students and next year they will be a minority in Algebra 2; a class filled with mostly juniors and seniors. Lately, some of their behaviors haven’t been progression towards that level and yesterday they pushed a little too hard.
Anyways, they were overwhelmed by the initial idea of going through 500 lockers. I didn’t say anything and after a couple minutes students were testing smaller cases. Eventually, they were victorious and tackled the problem.