3 years & up. These beautiful stones offer a tactile and visual way of introducing young children to number formation. Each stone is carefully engraved to provide important sensory feedback. Children will enjoy tracing each number with their finger building important motor-memory skills. Have children run to the number you call out for a fun outdoor learning experience that will encourage children to learn while they play. Each set contains 10 number stones (numbers 0-9) measuring 3 1/2" - 6" and an activity guide.