Gradually, once they are confident with drawing boxes to count objects, children start to write the number of boxes as a figure above the drawing.
Eventually they no longer need to draw all the boxes. They just draw one long box or bar and label it with the number. This step away from one-to-one representations to symbols is crucial and it may take a year or more for some children to become confident with it. But the benefits later on are worth it.
The Singapore Model Method
This model of numbers as labelled bars is known as the Singapore model, and it's a tool children can use to understand almost any concept in maths, including multiplication and division and even algebra.
Professor Lianghuo Fan, former editor-in-chief of Singapore's maths textbooks, has researched the reasons for Singapore's success in maths. As he puts it: "People have different views about the reasons for Singapore students' performance, but one thing that is universally agreed is that the Singapore model method is key."
You can see examples of different stages of the model in this slideshow: