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.
Chisholm Trail Variation
Free Quilt Block Pattern
This four patch quilt block is a slight variation of the Chisholm Trail quilt block. By a simple different arrangement of the light, dark and medium values of the fabrics it appears to be a totally different block. The block features simple patchwork, using only squares and half square triangles.
The sample quilt layouts show two very different quilts. One quilt uses a side by side block setting, while the second quilt sets the quilt blocks on point. Both quilts use sashing to separate the blocks, with very different results.
See also: Chisholm Trail