Most artists make a color sample chart of the paints they are going to use when they paint. I've seen a lot of them done by watercolor artists as a reference for them to see which colors look right together.
You don't really have to do that for acrylics but you still want a reference to go to so you can see which colors look really good together. That's where these little pocket paintings come into play.
You can try different colors and brush strokes out before you actually get to the canvas or larger painting you might want to make. I would call them acrylic sketchbooks.
You could take any of these samples and use it as a springboard for making a larger painting if you wanted. It's easier to make a smaller sample painting to try different things out. Besides, it's fun! These are more paintings from my third sketchbook. I make these from 140 lb coldpress watercolor paper and cut the paper 5.5" x 11" for six pieces. Then I fold them in half and sew or staple the center. That gives me 12 double pages that open up. Then I paint one side with bright colors and smear the paint in an interesting background. Sometimes I paint the page halves first and then put them together when they are dry. Then I take my time decorating the pages with details.
