The ultimate half-square triangle block tutorial

As promised, here is a tutorial for a very easy block which I did not invent but was shown how to make many years ago. It is very easy to chain piece, surprisingly quick to make, and you don't cut any triangles. If you divide your fabrics into light-medium-dark you can get interesting effects when the blocks are sewn together, and the layout possibilities are almost endless. Any half-square triangle layout looks good, and log cabin layouts will also work.

The fabric quantities given will make two 4in blocks at one time. Take note of pressing directions. If the blocks are pressed as shown, they will go together very easily.

From the fabric you wish to feature, cut two, 2-1/2in squares. I used bright colours and prints for mine.

From secondary fabric, cut two 2-1/2in by 3-1/2in rectangle. For this I used different bright green fabrics.

From background fabric cut one, 5-1/2in by 4-1/2in rectangle. I have used white fabric.

You will also need to make a template. Cut one, 4-1/2in square from template plastic or cardboard. Cut in half diagonally to make two triangles. If using cardboard it will need to be renewed from time to time, as the edges will wear away.

Sew each 2-1/2in square to the 2-1/2in side of the small rectangle. Press seams towards square. With squares at opposite ends, join two of these units to make the pieced rectangle unit shown.
On wrong side clip the seam allowance in the centre, being careful not to clip into the stitching.
Press seam allowance away from the square, as shown.
Place triangle template on wrong side of pieced rectangle, making sure it goes over the square in the corner. Using your preferred marker, draw a line along the long triangle edge. Repeat on the opposite corner. I used blue washout marker, but you can use a fine pencil or other marker.
With right sides together, place the pieced rectangle on top of the background 4-1/2in by 5-1/2in rectangle. Stitch along both drawn lines, as shown above and below.
You can see the sewn lines clearly from the back.
Using ruler and rotary cutter, cut 1/4in from each drawn line. Press seam toward large rectangle. This is what your blocks will look like when trimmed and pressed! You can also see the small strip of fabric that was trimmed, and is not needed.
This is a quilt I made several years ago, using this block. The background fabrics are different grey prints, secondary fabric is black solid, and I used several different bright tone-on-tone fabrics for the feature squares. The outer border is also pieced triangles using the background fabrics.

When I made my quilt pre-cut strips and squares had not been invented, but they could easily be used to make this block as many are 2-1/2in wide.

Enjoy making your blocks, and I would love to see pictures of the quilts when they are made!

Edited to add: My quilt was made (and dated) in 1998, and I learnt the technique before that. My quilt was also published as a project in 'Down Under Quilts" magazine in 2004. No doubt it has appeared in other sources....you can't keep a good idea down!