This lesson is on addition/subtraction of Algebraic Expressions. The lesson addresses the conceptual short-falls that cause so much trouble with fractions, but not in a way that students will recognize as remediation.
The slides are animated and the script is sparse, however, the language is rich. The powerpoint has notes on each slide that guide you through the lesson, highlighting things you can say, appropriate level of student interaction and so on. There is a video made from this lesson on my website, www.thebeardedmathman.com
Feel free to change what you like, use what works best and maybe make the lesson more than a day long.
There are great descriptions on the way the characters in the lesson are use, but they are powerful because students end up identifying with them (students of all ages).