# Locker Puzzle (VIDEO!)

In this two-part video, students of St. Mark’s School first act out the famous locker puzzle:

*100 lockers, all initially closed, lie along a corridor. Student 1 walks down the corridor and opens every locker. Then student 2 heads down and closes every second locker. Student 4 heads down next and changes the state of every third locker (closes it if is open, opens it if it is closed). She is followed by student 4 who changes every fourth locker, then student 5, student 6, and so on, all the way down to student 100 who touches every hundredth locker (namely, just the last one!). *

*What do the students see at the end of this result?*

Video number 2 explains what we see in video number 1.