Calgary Grids
So named because they were conceived while in Calgary. Their aim is to provide an unfamiliar context for enumerating things.

Here there are 9 points between A and B and 9 between A and C.
How many points of intersection are there altogether, in general?
It might be useful to consider how many lines there are.
The applet Calgary Grids provides different ways of 'seeing', that is stressing, or structuring attention, and so reaching different ways of expressing the same generality.
NOTE: the html file kept with the two Cindy-js files should work on most machines without using the Cinderella file.
How many points of intersection are there altogether, in general?
It might be useful to consider how many lines there are.
The applet Calgary Grids provides different ways of 'seeing', that is stressing, or structuring attention, and so reaching different ways of expressing the same generality.
NOTE: the html file kept with the two Cindy-js files should work on most machines without using the Cinderella file.