Have you heard of the locker problem? Check it out and ask us what we learned!
Imagine there are 20 lockers in the hallway and 20 students in your class. The first student walks down the hall and opens every locker. The second student closes every second locker. The third student changes every third locker. If it's closed, she opens it. If it's open she closes it. The pattern continues for all 20 students, so the 20th student changes the 20th locker.
How many lockers are touched by only two students? Why?
Which lockers are touched by the most students? Why?
Which lockers are left open at the end? Why?