The concept of negative numbers is introduced with this exercise.
Set includes wooden presentation tray with handles and six color coded boxes of bead material; one box containing 5 sets of colored bead stairs; one box containing 5 sets of negative bead stairs; one box containing 1 black and white bead stair; one box containing 23 golden ten bars; one box containing one red and white bead stair, and one box containing 23 gray ten bars.