The half square triangle unit is probably the most commonly used patch in a quilt block -- well it is second only to the square. It is made simply with two triangles, filling up half the square each -- hence the name. Take a quick look through this website, or in any quilting magazine, and you will start to notice that this half square triangle, regardless of its size, is present in more quilts than not.
Free Quilt Block Pattern
The Folded Corners quilt block is sort of an optical illusion, if you stick to colours in the same colour family. By using a slightly lighter shade of the darkest colour in the four corners of the block, it appears that each corner is folded into the centre -- hence the name of the block.
This easy quilt block is a standard nine patch utilizing half square triangles and flying geese patches -- both very commonly used patches in quiltmaking.
Both sample quilts illustrated use an on point layout with blank blocks included to showcase your quilting skills. Sashing separates the blocks on one of the quilts to feature some additional interest.
Check out these "optical illusion" blocks:
~ Formal Frame
~ Garden Square