Here are three drawing apps for the iPad. They seem to be pretty good for kids to be able to produce work. Thanks to Shannon Miller for mentioning these. There are different features available for each program. These product are free and can be used by students of all ages. They can play and create. Check them out.
Crayola's ColorStudio HD - You can make pages using animations, clip art, and free writing. Work can be saved or shared via email. The user can also save a picture of their page with a screen-capture.
Doodle Buddy for iPad - You can create pages of artwork. Doodle, stamp, add sounds and pictures to create you work. Share your work via e-mail or save a picture with a screen-capture.
SketchBook Express - A high-quality tool for creating art. Use tools to create pencil, pen, or brush marks. You can also use shapes to create lines, circles, squares, etc. You can even use layers to add depth to your creations.