|Create multiple boards. Swipe back and forth to access them|
Well, the answer is with the collaboration piece. Talkboard lets you share your board with other users. Then more than one user can collaborate on a board at the same time. Sharing is easy. Simply press the "+" on your board and choose between sending invitations by AirDrop, Messages, or Mail. If the user doesn't have the app, they will be sent to the App Store to download it. If Talkboard is already installed, the board will simply open in the app. You create a profile with just a name. You don't have to enter an email, so it's easier for younger students to use.
Once the board is shared, it's open for all the users. Write your own ideas, draw pictures, whatever. Any user can add or erase, so keep that in mind. I only tried sharing it with two people, but I imagine it would support more. But I think it would get pretty distracting if you had more than two or three students (or teachers) on there at the same time.
So there you go. Another free, simple tool that I feel has real practical applications in the classroom. Give it a try and be sure to let everyone know how it works for you.