What does a student's understanding look and sound like? We can ask students to explain an idea, a concept to us. We can ask them to draw a picture or diagram which helps to demonstrate their thinking. How about combining the audio and visuals to empower students to create videos to demonstrate their understanding?
Our First Graders are doing just this on the iPads using the ScreenChomp screencasting app. The topics for their videos are how we use combinations of coins to pay for things and how we use movement in the hands of clocks to tell time.
The screencast videos provide teachers very detailed assessments of student understanding. They can be used to pre-assess before teaching a lesson and to check for learning once the concept is taught.