Paper Princess,
When you draw a line across the diagonal of the square, layer the square with another square right sides together, and sew....you WILL sew 1/4" away from each side of the drawn line. Then you cut ON the drawn line to separate the HSTs.
I may not have given her the corrct size squares to begin with as there now appears to be a debate about what the finished size actually is supposed to be.
Jan in VA