Recently I decided to install Google SketchUp on all my computers because a) it's free and b) it's fairly easy to learn. I bought the Google Sketchup 7 for Dummies book (somehow I missed that there's a newer book for SketchUp 8) and tackled it over the following few weeks.
I got addicted. Software is like language. It was like I learned just enough vocabulary and verb conjugations that I could actually communicate. I started measuring everything in my classroom and apartment in order to model them in SketchUp.
The tricky part is figuring out a way for 12-14 year olds to catch on, too. I prefer 'challenges' to tutorials for a lot of reasons I won't go into here. But basically, at the beginning of class, I show the class some of the tools to use, then I give them a simple challenge that requires them to use those tools. The challenge is printed out, and includes a few pointers on how to use the tools. For most of the students, this is enough. For some, I'll have to wander around the lab answering their various questions.
Some of my documents are too big to upload, at least as far as I know just yet. I'll have to remove some of the helpful pictures. But here are the files:
They won't be enough for a teacher to learn the software. I recommend parting with the <$20 and getting the Dummies book. Below are some examples of student creations.