Kaizena is a great tool for adding voice comments to your students' documents and slides. When Kaizena originally launched it was designed for adding comments to Google Documents and Google Slides in the Chrome web browser. It then expanded to add support for Word files and PDFs. The latest update to Kaizena introduces support for commenting on physical documents through iPhones and iPads.
Kaizena's free iPad app and free iPhone app allows you to take a picture of a document, scan it, and upload it to Kaizena where you can then add voice comments to it. Of course, Kaizena's free iOS apps also support voice commenting on Google Documents, Word documents, and PDFs too.
Applications for Education
The latest update to Kaizena's iPad app could provide you with a good way to give students feedback on handwritten work. If you collect exams that have lengthy handwritten responses, Kaizena's iPad app could help you digitize those exam responses and speed up your process of providing students with feedback on their responses.