TuxPaint (includes Student Install)
TuxPaint is a graphics editor for 3-year-olds.
(Link to official site.)
However, a number of my students have enjoyed making graphics with it, as it uses a "Stamps" system so collages are fun and easy!
If you intend to use TuxPaint for your PortableApps assignment, then:
(TuxPaint and TuxTyping are part of the same group of "free and open source" software.)