I am a civil engineer in construction and during my career, I made a specialization in chemistry, physics. I give lessons in everything related to science: math, physics, chemistry... I have been teaching in Belgium and even in England since 2015. Generally I ask the student to give me the material he wants to work on and the best thing is for him to prepare his questions so that we can move forward faster instead of being blocked and at the risk of reviewing parts that he has already understood. (Although I once had a class where I completely re-explained the teacher's syllabus.) I also ask to become familiar with the material and nothing is better for that than doing a lot of exercises.