PowerPoint Apps

Today we discussed different apps that could be used with PowerPoint; ways to record audio and annotations so that they entire presentation can be accessed at school or at home.  I knew that PowerPoint is versatile and have recorded audio within that program, but haven't been able to record annotations along with the audio -- to be viewed at a later date.  I think this app would be most beneficial, especially as we continue to experiment with 'The Flipped Classroom.'