The software is so advanced, ELA teachers can split screen and freeze one paper, then display notes or revisions on the other side. All you need to work the ELMO or document camera is a laptop or computer, the slate a screen, and data projector.
The software will also do screen recordings or experiments or revision steps, problem-solving, etc. I'm going to encourage my Science and ELA teachers who already use the document camera to get the slate now. They will not necessarily need an interactive board.