More explanation on BTS I'm Confused

Question

More explanation on how many course

Answer 1

If you want to get bts badge continuously complete 15 lessons for 15 days to maintain this tree and then you will successfully get the badge its simple

edit :

read the faq

https://get.sololearn.com/back-to-school/faq

Answer 2

https://www.sololearn.com/post/499747/?ref=app

Check this
Nice explanation by Lord Krishna sir

Answer 3

https://code.sololearn.com/WhxS7Gd2NnlF/?ref=app

Answer 4

Please let me know different between lesson and modules