SketchUp is the simplest free 3D modeling software on the web — no strings attached. Bring your 3D design online, and have your SketchUp projects with you wherever you go. You don’t need thousands of bells and whistles to draw in 3D... All you need is your idea, and room to draw.
https://edu.sketchup.com/app (this is the link to use SketchUp, you do not need to download anything)
Video Tutorials
Self-Paced Tutorials
SketchUp Skill Builder
Helpful Links
SketchUp Website: http://www.sketchup.com/
Download SketchUp at Home: http://www.sketchup.com/intl/en/download/gsu.html