My grade 11 textbook never mentioned about inertial frame, non- inertial frame, rotating frame of reference and so son.The derivation of centripetal acceleration was very intuitive.This derivation was given after Laws of Inertia and other Newton's laws of motion.Ideas like cross product and dot product are not clearly given in the textbook After the not-so-explanatory derivation of centripetal acceleration and the corresponding force, we have the discussion of centrifugal force.... "Centifugal Reaction According to Newton’s third law of motion, for every action there is an equal and opposite reaction. The equal and opposite reaction to the centripetal force is called centrifugal reaction, because it tends to take the body away from the centre. In fact, the centrifugal reaction is a pseudo or apparent force, acts or assumed to act because of the acceleration of the rotating body. In the case of a stone tied to the end of the string is whirled in a circular path, not only the stone is acted upon by a force (centripetal force) along the string towards the centre, but the stone also exerts an equal and opposite force on the hand (centrifugal force) away from the centre, along the string. On releasing the string, the tension disappears and the stone flies off tangentially to the circular path along a straight line as enuciated by Newton’s first law of motion. When a car is turning round a corner, the person sitting inside the car experiences an outward force. It is because of the fact that no centripetal force is supplied by the person. Therefore, to avoid the outward force, the person should exert an inward force." Something is wrong with this explanation.First there is no reference about rotating frame which is a non-inertial frame.The author talks about validity of Newton's laws without the concern of the nature of frame.I think this is weak description..Iam a high school passout and I have found some conceptual errors. Physics is taught the worst possible way in my textbook. I myself took the initiative to learn about frames of references. I have given the link to my textbook..Please rate this textbook. http://www.textbooksonline.tn.nic.in/Books/11/Std11-Phys-EM-1.pdf Also, if there is some logical inconsistency of this explanation, please point it.I want to take up the matter to the educational officers concerned..