Students can demonstrate their algebraic solutions on the tray and later, store loose pieces in the attached storage unit to ensure they don't get misplaced. A great all-in-one solution for the classroom. All positive pieces are represented in blue, negative pieces are red. 88 pieces with tray. Pieces include: 8 X2 squares (4 red, 4 blue), 20 X tiles (10 red, 10 blue) and 60 unit chips (30 red, 30 blue).