If you run up a flight of stairs you do work since you are applying an upward force, equal to your weight, through a distance, equal to the vertical height you climb. The purpose of this activity is to measure the amount of power a student can develop while climbing a flight of stairs. Next you must find a flight of stairs where lots of children running and shouting won't interrupt other classes. Using string and a meter stick or any method you choose, find out the vertical height of the stairs. Counting the stairs and measuring the height of each also works.
Heavier people can go slower and still develop the same amount of power.
The final answer will be in watts. In high school,unusually fast and strong people might approach 1000 watts. We are fairly certain everyone can develop more power than 10 watts. So, depending upon the size of your students, you should expect the power they develop to be roughly 100 watts. After the students have completed the activity, ask them how long they think they could keep running up stairs at the same speed.