Sustainability
Teachers and practitioners can be sure that every time young children use their own graphics to communicate their mathematical thinking, they do so with personal meaning and genuine understanding of their marks, signs and symbols. Having the freedom to choose if and how they will do so, means that children choose the media that is most appropriate for the context of their maths at the time (e.g., various types of paper, child-height whiteboards, a surface outside). As a consequence, there is no need to purchase any published resources.
The result of this openness is that what each child does is a true reflection of their current understanding of the abstract mathematical language of mathematics, as they journey towards standard mathematical written symbols and more advanced layouts for all areas maths, including problem-solving, calculations and data handling. Saving (or photographing) these examples will also provide wonderful material for formative assessment (see for example our taxonomy, and the children's examples below).