Geometry Puzzle

11-14 year olds | two hours

Though you’ve probably seen these in a math classroom before, tangrams should not just be left at school. These fun puzzles get kids thinking about different shapes and how they can fit together. Plus, putting together this project will add a whole new dimension to the puzzle they play with.

What You'll Need

  • balsa wood (found at craft supply stores)
  • craft knife
  • sharp pencil
  • ruler
  • sandpaper
  • paint


1. Cut a piece of balsa wood to a 12 x 12 cm square.
2. With a pencil and ruler, draw a faint 3 centimetre grid on the wood. The drawing must be very faint, since balsa wood is impressionable and marks will stay.
3. To do this, measure with a ruler 3 centimetres away from the corner make a dot. Measure 3 cm from this dot. Make a dot. Measure 3 cm from this dot. Make a dot.
4. Now draw lines vertically that line up with these dots. Repeat this process with horizontal lines.
5. Once you have the grid, draw five lines heavily. See illustration for these lines and also read along.
6. The first line is a diagonal across the middle of the square. It goes through the very centre of the grid. It’s points are top right to bottom left.
7. The second line is another diagonal, smaller and to the right of the first. It runs through the centre of two squares, from end to end.
8. For the third line, start making a diagonal opposite to the first line, but stop at the second line. The points are top left, bisecting the first line in the centre, and stopping when it intersects with the second line in the centre.
9. Count one box over from the bottom left box. Draw the fourth line in this box. It should be parallel to the third line and should not go outside its bottom left-middle box.
10. For the last line, darken the light grid line that runs between the first line and the second line and connects them. Do not continue the line beyond these first two.
11. Lightly erase the grid.
12. Using the knife and ruler, cut out the lines in generally the same order in which you drew them, forming seven shapes. Go slowly.
13. Lightly sand the shapes so there are no sharp edges.
14. Paint the shapes with colours of your choosing and let dry.
15. Play. This games is hundreds of years old and over 5,900 problems and shapes have been made with it, so it won’t get old!

Tags: model making

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