It is a common learning tool for children in Montessori education. In the professional Montessori teaching, the three-step card is also called A card, B card and AB card. In Montessori's teaching method, a card is an image picture of a thing; B card is the name of a thing; AB card is a combination card of the image and name of a thing.

In fact, the three-step card is the concrete embodiment of the essence of Montessori education. Montessori education law tells us that as teachers, we must build a bridge between abstract symbols and concrete food, and the three-step card is the bridge between concrete food and abstract symbols.