Khan Academy

https://www.khanacademy.org/

Functionality: Khan Academy offers practice exercises, instructional videos, and a personalized learning dashboard that empower learners to study at their own pace in and outside of the classroom. Also provides support for teachers: find standards-aligned content, assign practice exercises, videos and articles, track student progress.

System Requirements: Works on most web browsers. Has iOS and Android apps.

Delivery Methods Supported: Supports lecturing, tutorials, revision

Subject Applicability: Science, computing, arts and humanities, economics, reading and language arts, life skills, test prep

Security Concerns: None

Pricing Model: Free, requires account to be created