Originally Posted by Rose Marie

You use large squares and just draw a line from each corner to make an X. Sew 1/4 inch on each side of lines. Cut in half at the middle both ways + then on lines. You will have 8 half square triangles. Use a 6 inch sq for 2 1/2 inch half squares. Add 2 inchs for each size. 8 inch squares makes 3 1/2 inch HST. They are slightly over sized so you square up with her ruler.
The ruler gives all sizes for both HST and quarter triangle sqs.