Came across Office Lens after a post from @ictevangelist and then again saw it presented as part of #appsharelive during April 2016.
Lens basically allows you to create a picture of a board or other display and then corrects for the angle at which the photo is taken. For example you might have the students recording their ideas on a whiteboard and you might want to then keep a record of this by photographing it. Lens allows you to take the photo without too much concern for your positioning when taking the photo. The app itself corrects for where you are not directly in front of the board.
I have also found it very useful at events and conferences where you can’t control your position in reference to the screen. With Lens you can just take the photo and allow the app to correct for the angle between where you take the photo and the screen you are trying to photograph.