Who would think problem solving could be so much fun? An exciting marble rolling building set, that is both educational and fun. Hardwood blocks with grooves and holes are combined in a variety of ways with the end result of 6 marbles ringing the bell to signal success. Helps educates the laws of structural engineering and stimulates spatial thinking. This ball track includes 42 pieces. Shapes are in standard measurements: 1 3/4 x 1 3/4 and all HABA block sets are compatible and can be combined. Made of solid, natural, untreated beech wood.