I'm working on my K-5 math endorsement this year, and one of my assignments is to create a presentation about the Chinese number system. Here's a simple video I made using Show Me to demonstrate computations with Chinese numbers (warning to those who can actually speak/write Chinese -- my calligraphy with the Chinese numbers is not very good!):
The app is very user friendly, although it does require a sign in to be able to save your videos. Once videos are saved, they can be deleted (unlike ScreenChomp -- my former go-to app), and there's a download feature in beta so you can download videos and embed them in things like Prezis. You can also adjust the sharing settings of videos to keep some private should you so desire.
In my classroom, we use this app to make math movies to explain different math concepts. I'm outsourcing video creation to my students this year, and I plan to post some of their videos on my class website as homework help for future years. It's also a great way to assess student understanding because I can really learn a lot by what they're able to explain or not explain, but that's a different post...
Do you use Show Me or similar apps in your classroom? I'd love to hear about it in the comments!