A Half Square Triangle block is made using 2 fabric squares of the same size but different fabrics.

Place the 2 fabrics on top of each other with the right sides together.
Draw or mark a diagonal line from corner to corner on the wrong side of one of the fabrics only.

Sew 2 lines parallel to the drawn line, one on each side. Each must be ¼” from the drawn line.
After sewing, cut on the drawn line. Press the pairs open with the seam allowance to one side.
You will have 2 Half Square Triangle blocks.
