Partial Products Puzzle Box

About Partial Products Puzzle Box

Partial Products Puzzle Box writes each piece of a multiplication on its own line and adds them at the bottom. It is the same decomposition our Grid Method Multiply Lab lays out across a grid, deliberately presented the other way round, because the vertical list is the step between the grid and the compact column algorithm that eventually replaces both. Once the partial products are stacked, adding them is exactly what column multiplication does — silently, in a way that is very hard to see. A child who has written the list out a few dozen times has a much better chance of recognising what the compact method is doing when it arrives, rather than accepting it as a sequence of moves to memorise. Partial products is the term used in American Common Core material, and the vertical layout here matches how it is set out in those classrooms; the grid version carries the UK and Australian name for the same idea. Each row names one multiplication and the child places its answer, with the total underneath. Two-digit by one-digit to begin with, and two-digit by two-digit from the fourth level, where four partial products appear and the list stops being something a child can shortcut in their head. Every empty cell carries a clue naming the multiplication being asked for, with a fuller hint behind a button. Grids are worked by tap or keyboard, every cell is announced to screen readers, and a wrong number flashes and can be replaced with nothing lost. Free, no sign-up, no advertising to children.