Recently, I received a request by a teacher wondering if there was a way kids could practice annotating text in a digital format. Immediately I thought of Google Docs. Of course, there are limitations but using the comment feature along with other editing tools (underline, highlight superscripts, etc..) we had good success taking text annotation to the digital level. There are other mediums too, such a Edmodo that do a nice job allowing commenting and annotating. Click on this sample, designed for the class, to see how we used common Docs tools to mark-up a given piece of text.