The Scratch website has lots of introductory videos to learn how to make a sprite glide, spin, change colour, and plenty of other nifty features. It's also worth looking at the Tutorials section since the Cards and Guides give detailed explanations to help you learn how to code.
There are some great ideas you can use in your class on this site. It also has a How-To Guide for Beginners you can download to get you started with coding.
I was a little lost when it came time to assess what my students had learned after teaching them how to code. This ScratchEd sites gives you lots of examples of how to see what your students understand, at the elementary, middle, and secondary levels.
Many of my students ordered this book from Scholastic and our school library has a copy too. There are lots of fun projects to get students started that you can adapt to suit your curriculum--modifying the Happy Birthday card to a Mother's or Father's Day card for starters. We have tried a lot of these ideas in our lunchtime Coding Club too.
This site, part of Coding in the Elementary Grades, links you to all sorts of different lessons you can try with younger students. There are many applications for the classroom like storytelling, problem solving, and math.