Upload videos or link to YouTube. Add video, audio, or text comments at the exact place in the video where you want it. The creator can also add buttons for simpler comments, such as "awesome" or "I don't understand."
Limitations: As of 6/9/2014, the audio and video comments don't seem to work.
Classroom Salon is a document and video annotation system. All your course documents and videos can be annotated by students using salon's annotation tools. They can comment on specific words, sentences and paragraphs and also comment on video frames. Salon aggregates all these annotations to provide amazing insights into student thinking.
Sync presentations to all devices, add comments and discussion on slides.
Useful in live classroom.
Limitations: Presentation only saved for 4 hours in free version.
Annotate texts online using colored highlighters, text comments, and tags. Collaborate with other users and groups. Requires creating a free account to share the texts.
Upload a PDF and add video, images, audio, comments, and quizzes. (You can also annotate using a pen, but only you will see those annotations.) You can also create classes and add the PDFs and students to them.
Limitations: With the free account, you cannot make a document private.
TodaysMeet helps you embrace the backchannel and connect with your audience in realtime.
Encourage the room to use the live stream to make comments, ask questions, and use that feedback to tailor your presentation, sharpen your points, and address audience needs.
Use books and articles in English or import your own in any language. You can add annotations and questions to the articles, plus create quizzes. Students can also comment on the articles.
Limitations: Free accounts can only import 3 articles per month. Presumably, you can use as many of the existing articles and books as you want, but they are only in English.
Quickly create a web page by
1) Send an email to p@mailp.in.
2) Get a sharable URL of a web page, which contains full content of the email message, including attachments. It also allows comments.
Four classrooms are connected in a "quad" and comment on each other's blogs.
Limitations: To sign up, the instructor includes his/her name and email address in a public Google doc.
Platform for inspiring writing, posting writing, commenting on writing, and revising/editing writing.
Limitations: 40 students and 5 posts for a teacher with a free account.
Computing Languages are languages too! Check out this great tutorial that will help you understand and perfect the basics of HTML so you can build a better comment! Also offers tutorials for Java, Jquery, and other programming languages.