Go 3-D with your domino games or periodic table! These colorful, flat rectangular tiles have a slot on each end and two on each side, allowing other tiles to be easily joined to them at a 90-degree angle to make sturdy connections. The periodic table set is recommended for children ages 10 to 12 and contains 150 color-coded wooden pieces - 118 elements plus 32 circular connectors. Element tiles are approx. 2.5" to 3" long and display the element's symbol, atomic number, and atomic weight.