TopNotes is an iPad app that allows you to take notes, insert images, highlight and more all within the app. Pair with an Apple TV and allow your students to show their work with the class. Does not have the recording capability of ShowMe, but it's very easy to use.
The demo video shows the process of opening the app, creating a note, & inserting a photo. If you still have questions, let me know and I'll come by your classroom for a live demo!
Great app for: showing math work, storytelling, annotating images.