Mindstuff Question

Physical and graphical artifacts can be correlated in a relatively concrete manner to concepts such as geometry, spatial skills, and arithmetic. What do you consider to be some interesting examples of transitional objects, either physical or virtual, that have been created or envisioned to act as cognitive bridges to help teach children more abstract concepts than those mentioned above?

Why I find this interesting:

Crafts, whether augmented with computing power or not, seem well suited to teaching children skills which have corollaries in the physical world. There are some important skills and concepts that do not have physically tangible manifestations. It seems that a great deal of innovative thinking would be required to represent such concepts in a way that a child can connect to in a manner similar to how they would connect to a toy.