Empty Glasses


Need a quick hands on QR activity?  Try this one posted on I-Tunes University: a  Math Challenge from the University of Warwick called Empty Glasses.


  1. Five glasses (per small group of four to five advisory students) 15-25.
  2. Water
  3. Food coloring
  4. students and their active brains

Set Up:

For each group of students, set up the five glasses as shown above. Three full glasses next to one another then two empty glasses.  You can fill with water (using food coloring if you want to make it more visible).  You may want to discuss some rules about appropriate use of the materials with the groups.

Ask the group to have one or more people take notes as the activity begins.  (Students may want to rotate this).

Pose The Challenge:

“How can you arrange them so that they are alternately full and empty by moving only one glass.”

Encourage students to try to discuss and test as many solutions as they can.  Have the note taker(s) document the discussion and tests. A critical part about this challenge is the set up and encouraging students to keep solutions focused and to persist in the process – learning as they go along.  If they have interesting ideas and reasons for trying a solution, that is very important.  The answer is not as important as the process and the reasoning. Play and explore possibility.

I don’t know if there are multiple solutions to this challenge; I imagine that there are.  However, the solution posted by the University of Warwick is also on I-Tunes.  It involves pouring!

Solution to Empty Glasses