They are made available here for teachers who might wish to present
these investigations to their students using the Excel files.
But if these examples stimulate other similar presentations, so
much the better.
"Products on a Number Grid" invites students to notice that the
product formed by the values in opposite corners of a rectangle on
a number grid maintain a constant difference for all positions of a
rectangle of a fixed size.
"Number Grid Functions" is a more general treatment. Here students
are invited to consider the effect of translations around a number
grid of varying width, first of a simple sum, but beyond that to
other operations or functions.