Scratch Lesson Activities:
A good introductory video to scratch:
http://openbookproject.net/courses/scratch/day01.html

Anticipatory idea for lessons:
http://armorgames.com/play/2205/light-bot - online game similar to Harold the robot, tell the robot how to light up a blue square.
http://www.omsi.ifo/visit/tech/activities.cfm# - robot obstacle course