Bury these dinosaur bones in sand, soil or even water, and they will instantly appeal to children's instincts to explore, investigate, collect, compare and measure. Cast from a durable unique mix, each bone increases in size by 2cm and can be used to introduce the concept of measurement, doubling and halving. Includes 16 bones - two of each size: 6, 8, 10, 12, 14, 16, 18 and 20cm.