Typing Club is a free program! It has many, many lessons on typing that include videos, visuals, and exercises. You can assign students a few lessons a day. Each of them are pretty quick and straight forward.
Dance Mat Typing
Dance Mat Typing is a fun, interactive way to learn touch typing. Students start by learning the home row keys. Each stage builds on previous lessons, introducing new letters as you progress. Soon, students will touch typing like an expert!