http://nptel.ac.in/

https://www.coursera.org/

http://hcl.harvard.edu/

https://www.khanacademy.org/

http://www.knowledgeoftoday.org/2014/07/list-of-40-free-educational-websites.html?m=1" target=

https://www.topuniversities.com/blog/33-useful-websites-students

http://www.sitesforteachers.com/index.html

https://www.scholastic.com/teachers/articles/teaching-content/25-best-websites-teachers/