I have had this amazing app since last semester, maybe even last school year, but never found time to use it for my students. There was a common question last week from the physics homework on echoes in a canyon and determining the distance across a canyon. I thought this was a great opportunity to use the app so I took a picture of the question using the app and wrote an explanation while recording my audio explanation at the same time. Pretty cool!
Here's a link to their website: