Listly
Listly by Melanie Burford
Here is a list of apps that students could use to annotate or record voices, etc.
You can create videos with this app or just use it to annotate over pictures. I made a Frayer model example using this app.
This one's free! Use this app to record what you know and explain what you know to others. You could also use this app for the mind mapping example (see Prezi).