Mycbsegide.com is one of the best teacher for cbse students. Personally speaking, I use this site since 3 years . It covers the whole syllabus and everything. You may get best guidelines and support . It contains syllabus , important notes, sample papers, last year papers. And almost everything that supports your studies .You may also download ’mycbseguide’ app , available on playstore.This is probabily the best mentor for cbse students