Do not skip the High Order Thinking Skills questions at the end of the Lakhmir Singh chapters. These questions test your actual understanding rather than rote memorization.
While the NCERT textbook provides the core curriculum, Lakhmir Singh's volume breaks down complex jargon into language that is easily understood by an 11- or 12-year-old. lakhmir singh class 6 science book pdf link
Discovery of magnets, magnetic and non-magnetic materials, poles of a magnet, and making a compass. Do not skip the High Order Thinking Skills