On the second page at the bottom it gives you the cutting instructions for each color:
Color 1: Color 1 needs: one 7" x 14" strip AND one 3-7/8" x 11-5/8" strip
Color 3: Color 3 needs: one 3-1/2" x 26" strip AND one 3-7/8" x 11-5/8" strip
You are stacking the 3 7/8 X 11 5/8 inch pieces of colors 1 and 3 to make the half square triangles. :)