So GridMaths.com is in open beta, now works reasonably well on iPad and recent desktop browsers. Android browser support coming sometime soon.
Heres a pic my 9yo created while testing things out on the iPad.. with the obligatory battle scene [ dad vs browser quirks ? ] :
Here’s a couple of sheets on how I like to present long multiplication…
Firstly a concrete rectangle where you can actually count the squares to satisfy yourself its right…
Then move to a more compact form, which still shows the rectangle grid, but not to scale..
This shows that lots of digits should not induce panic.. the same systematic approach works [ which is why computers can do multiplication so well ].
I think having the box grid is a nice way to remember where all the pieces come from [ single digit products ]. Also I think it really helps to use the blank grid spaces, rather than fill in every 0.
The lattice method is slightly more compact, but I think this box approach reminds students of whats really going on.
Thanks for all the emails and encouragement so far as I build this.
Enjoy, and let me know how your using GridMaths.