I have never heard of the app, 'Explain Everything' before.
From playing around with it, my initial reaction is that it is an advanced form of PowerPoint - but I feel that this is probably me being ignorant about the features of the app and its potential.
I've tried to create my own 'Slideshow' for my presentation. As you can see, I've just used it as another method for a presentation and it could have been achieved through a number of different programs. You've also probably noticed how absolutely awful my 'presentation' is - I couldn't really get to grips with it.
I hope to spend some more time with the app and exploring its features - such as the recording device, which I think could be very useful e.g. having a presentation with an explanation over it, it could be a lecture at home. Although I doubt I could get my students to listen to me talking about Law in their own time, it's hard enough to get their attention in the 1 hour a day that I have them.
