Setting the StageThe students have created several other projects with Scratch in earlier grades. The projects revolved around moving sprites and programming a simple dress up game.
Thinking About ShapesWe walked through steps to create a square using the pen commands. I have laid out the lesson on this wiki page. Once they had an idea of how the commands worked, they really enjoyed experimenting with the handout (also on wiki) and seeing how changes to the command blocks changed the shapes drawn on the screen.
Exploring Multiple RepeatsOnce basic shapes are mastered, the students will explore creating spirals by embedding shapes in repeat statements and modifying the angle at which the sprite starts. They will extend those spirals by changing the pen color and pen size. The lesson handout is on this wiki page.
Further ExtensionsI am in the process of creating a few more handouts for students who work through these first two projects. All of the previous concepts work on the basis of 360 degree turns to complete a regular shape such as a square, pentagon, or octagon.