mySchoolNotebook is a note taking service the lets students, or anyone else, take notes, edit and format them, and even add images and videos to the notes.
The free plan does have some limits, but still has a lot of features, including notebook sharing, mobile access and offline access. The paid account adds unlimited notebooks, as well as a few other features, for only $2/month.
There are Android and iOS apps for it also, as well as a web app. You can create different notebooks for different classes, etc.
This is a great app for students to get their notes digital.