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 Lightning quilt block evokes an image of just what you think it would -- a look of a lightning flash. But, depending on whether you set the blocks on point or side by side, you can achieve an entirely different look. Don't forget also to try flipping the blocks, as I did in the sample straight setting, so that a secondary pattern appears.
This quilt block is made entirely of half square triangles so it falls into the easy category as well as the intermediate category, due to the number of pieces needed to create the block.