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.
Flock of Birds
Free Quilt Block Pattern
The Flock of Birds quilt block is another example of using simple shapes and rotations to create a new look. This quilt block contains only squares and half square triangles so on the surface, it is an easy block. However, I have added it to the category of intermediate difficulty because care must be taken to achieve an accurate quarter inch seam allowance in order for the patches to match up where needed.
The two sample quilts illustrated show just how different your quilt can be from someone else's. By rotating the individual blocks, whether you set them in a straight, side-by-side setting or on point, the looks you can achieve are endless.