Concept
Version 6
Created by Boundless
Chalkboards, Flip Charts, and Transparencies
Source
Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:
"All sizes | Chalkboard | Flickr - Photo Sharing!."
http://www.flickr.com/photos/nirak/3902673698/sizes/l/
Flickr
CC BY.