Montessori Educational Toy Wooden Domino Number Puzzles Set. Self-Correcting Puzzle Pieces Teach Counting and Numeral Recognition. Help Your Child Learn Math Skills and Have Fun! Made with eco-friendly and sustainably-sourced wood. Self-correcting domino number puzzles teach basic counting and numeral recognition skills. High-quality, durable puzzle pieces contained in their own box with a sliding top. Easy for kids to open and close on their own. Individual puzzles are about 3 inches across and fit together in a 10-inch-long box. Handmade in the Czech Republic.