Clarisketch is a free Android app that has great potential for classroom use. The app allows you to take a picture or pull one from your device's camera roll then add your voice to it. While you are talking about your picture you can draw on it to highlight sections of it. Completed projects are shared as links to the video file hosted on Clarisketch. You can share the link to your Clarisketch video and have it play on nearly any device that has a web browser. See my sample here.
Applications for Education
Clarisketch could be a great app for teachers to use to create short tutorials. Students could use the app to create short stories about their pictures. You could also have students use Clarisketch to explain things like how to solve a math problem or the significance of a place featured on a map.