KG Primary Dots
If you've ever purchased handwriting books or printables, this is very likely the font that was used. It seems to be the go to font when creating that sort of workbook for students. While the font is free for personal use, which is great for teachers, the commercial use version is surprisingly affordable. As of this writing, the commercial version is only $5 at FontSpring.
Be sure to take a look at all four variations of this font. The default example is the KG Primary Dots font which is a great font for students to use when practicing their lettering. The other three variations are the same font, but inside a set of lines to help students keep their lettering the correct height.
This download contains 4 font faces