Graph paper, 1 cm

A centimeter square is big enough to write a whole two-digit number into, which makes this the right graph paper for column arithmetic as well as for area. A child who puts one digit in each square keeps the columns lined up without being told to, and a column that drifts is most of what goes wrong in a long sum.

It is also the paper for area and perimeter the first time either is taught. A rectangle drawn 7 squares by 4 squares has an area a child can count and a perimeter they can walk round with a finger, and both of those are lost the moment the squares are a quarter of an inch and the label says centimeters.

The rules are drawn as real strokes at real sizes — not a picture of lines, and not a background tint. That matters more than it sounds: browsers drop background graphics when printing unless the reader has gone looking for the setting, so ruled paper made the obvious way looks perfect on screen and comes out of the printer blank. Put a ruler on this one. It is the size it says it is.

This sheet is set for US Letter — 8.5 × 11 inches. Paper size is not a preference here: sent to a printer loaded with something else, the browser shrinks the page to fit, and a ruling that has been shrunk is no longer the size it was chosen for. So there is a second copy of this sheet, ruled identically and measured for A4.