Talkboard is a free iPad app from Citrix. Talkboard enables you to sketch on whiteboard while talking to collaborators at the same time. You can invite people to your talk board by sending them an email from the app, by Airdrop, or by posting a link for them them to click on their iPads.
Within Talkboard you can create projects. Each project can have multiple whiteboards. This makes it a nice tool for students who are working together on a large project. By creating multiple boards within a project students are essentially storyboarding or outlining each phase of their project.
Talkboard could be a good app for providing remote homework assistance. It also has great potential as an app for remote peer tutoring.