Children's book - One is a Snail, Ten is a Crab. In this “counting by feet book,” one is a snail, two is a person, four is a dog, six is an insect, eight is a spider, and ten is a crab. Numbers are represented as combinations of animal feet. Question - how many different ways can you make ten? The multiple solutions reflect an understanding of "ten-ness," making computation easier in later grades.