Scratch
This curriculum uses the "Examples" to teach students using 24 programs, each introducing a new concept. Copying programs makes students immediately successful and creates engagement and self-confidence. They quickly begin to make changes and explore independently. The "Projects and Challenges" are formative assessments that cover the most basic skills up to advanced topics like prime number generators. Over the last 6 years I've used this with grades 3-8 and it's always fun for the students. Who doesn't like to get it right all the time...