In our opinion, these are the five best, newly developed XBlocks:
- Staff Graded Assignment. Students are invited to upload documents as a way to encapsulate their work on their assignments. Instructors download the files and grade them.
- Mentoring. It automates the workflow of real-life mentoring within an edX course. It supports free-form answers, multiple choice and response questions, rating scales and progression tracking.
- Ooyala Video Player. It places Ooyala videos into edX courses. It supports transcripts, overlays –to place raw text or HTML content at a specific moment in your video– and player tokens –to secure your video content using a token with an expiration time.
- Drag and Drop. Students are required to drag and drop texts or images into different sections as specified by the assignment.
- Image Explorer. It allows display tool tips of an image within the course content.
See a more complete list here. The official explanation of XBlock architecture is at this URL.