Yeah, the assets in Unity is going to be a pain. That's the advangage of 2D programs such as Scratch, Game Maker or Flash: they can just open paint and doodle themselves.
There are a couple of assets included with Unity, and you can find 3D models for free on the web, but it's not going to be a piece of cake (especially for import/export formats)...
suggestions wanted: teaching game design to middle schoolers
Re: suggestions wanted: teaching game design to middle schoolers
Just found out I actually won't have the 7th graders, 5th and 6th only...so... yeah. I'm going to focus on Scratch for now, maybe see how much I can structure a Unity class to bring it down to level, I might have to scrap the Unity idea if its not going to work, but I'm still considering it.