If you can't remember how to make tangrams from a square there are many internet sites to help you out. This is a nice one you can use to make a paper template. Of course, my foam rectangles were larger than the A4 paper I started with, so I used it as a reference instead.
Make yourself a square. Then use the corners to mark one large and two smaller triangles. You can be neat about it and draw the shapes with a pencil, or you can wing it like I mostly did.
Cut these out, and put the two smaller triangles aside. With the longer side of the triangle at the top, fold up the point to give your self a crease. Here if you measured it might be more accurate but for my purposes this is close enough. Give the foam a good press to make a line.
Then cut along this line.
Put the bottom triangle aside. Now fold the top piece in half lenthwise.
Cut down the middle. Then for the right piece, I used my trusty quilting ruler to line up with the bottom right corner, to cut it into a square and triangle, like so:
Put the square aside. Take the small triangle and use it as a template for your last cut. Flip it over, and place the right angle on top of the right angle of the remaining piece on the left.
One last cut, and you're all done! Hurray!
Now you've done one, it's really fast to use the pieces as templates to cut out some more.
Aren't they pretty? I'm going to make up a bunch of cards with a gazillion tangram ideas that the kids can try to copy. In the meantime, they can freestyle.
