Over and over again, half-square triangles (aka HSTs) are explained.  Over and over again, beginning quilters continue to have trouble making them.  I will add myself to debunk the HST myth.  It’s not magic, it’s just MATH!

Start with two equal-sized squares*.  On the back side of the lightest square, draw a diagonal line, corner-to-corner, ONE (1) time.

Diagonal line.

With right sides together, sew 1/4″ on either side of the line you drew.

Using a ruler and your rotary cutter, cut the square into triangles, ON the line you drew.

Two triangles.

Open them up and press toward the darkest fabric.  You have now made two HSTs!

*A little quilter’s tip – cut the squares a tad larger than your pattern calls for.  Once you have pressed your HSTs, you can then square them up to be the exact finished size your pattern requires.