Pennsylvania Department of Education
Counting People
Students practice counting. In this counting activity, students are used to help visually represent a number for their classmates.
Cut the Knot
Cut the Knot: 3 Glasses Puzzle
Challenge students to a well-known riddle involving three different-sized glasses, some water, and a goal of a certain amount to be measured out. At this site, students can actually "pour" the water back and forth to solve the problem.