You may also want to consider Noteflight. It's web based (noteflight.com) and now works on iPads. It may be a faster to write on Noteflight, but you need to be online. It's also able to write more complex notation.
They have a learning edition (there you need to pay), where the teacher is able to post assignments and when the students log in each one is presented with a fresh copy of the assignment. You can then check each students's work, add comments, etc.