Pencil
Basic paint-style program comparable to a heavily trimmed version of Photoshop or GIMP.
If you need more help or have questions, please contact us or check out our Technical Support page and TechFairy Tutorials OAC Blog where we may have specific Education-geared tutorials and videos.
Available on both Mac and PC.
Pencil product site - site unfortunately appears to be blocked, at least from the UVic server.
Pencil2D product site - an offshoot of the original program, created by different developpers.