To make an octagon in a square, first draw a square. Then draw diagonals from each corner to the opposite side to divide the square into 8 equal triangles. Finally, use a compass set to half the length of a diagonal to arc 8 marks from the corners and join them up to form the octagon inside the original square.

1. Make an Octagon in a square
Step 1. Draw the
square
Step 2. Draw diagonals
Step 3. Set the
compass to ½ the
diagonal and mark
them from each corner
Step 4. Join up the
corners