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 Double Star quilt block is comprised of two star units -- one star inside the other. The stars are each a Sawtooth Star which is a popular quilt block all on its own. This block takes the Sawtooth Star to a new level.
The Double Star is comprised of lots of flying geese units and could be considered an intermediate level quilt block due to the number and size of the individual pieces. However, by taking care with sewing an accurate quarter inch seam allowance, this quilt block will be together in no time.
See also ~ Double Star #2