The SAMR Model (Substitution, Augmentation, Modification, Redefinition), created by Ruben R. Puentedura is a relatively new teaching and learning model designed specifically for technology. It's an incredibly valuable theory to understand, as it will allow any teacher to use technology to its full extent and beyond. Where many will often substitute a task like writing on paper to typing notes in Word or Pages; entirely new tasks can be created that were once inconceivable.
I have attached some links below to help you better understand SAMR.
Dr Ruben's Weblog http://www.hippasus.com/rrpweblog/
DETWA's overview on SAMR and other learning theories
iPad apps classified according to SAMR