As secondary school teacher for over 26 years in Hong Kong, teaching mainly Physics with syllabuses from HKCEE, HKALE and HKDSE and Maths (HKCEE & HKALE). As to typical problem students may face is misconception. It is better to understand the misconceptions established from students so as to improve their misunderstanding of basic concepts in Physics and Maths. One of the common mistakes done by students is the wrong use of formulae for problem-solving due to ignoring the failure in meeting the given conditions. For example, when applying Boyle’s Law, the given conditions are fixed mass of gas and  constant temperature that should be checked met or not, especially neglecting the occasional leakage of gas or any changes in temperature may lead to errors.