I'm a bit confused about some of the international criteria. I'll be applying to colleges this year and I want a career in STEM. I'm thinking BSc in Physics and Mathematics. But I've only taken two years of Maths, Physics, Chem and Bio in my first two years of High School. Then I took Principles of Accounting, commerce, economics, business maths, business statistics, commercial geography and banking in my junior and senior year. I'm in Pakistan and I've always wanted to study abroad. Can you tell me what the criteria is in your respective countries? Please, if possible, mention your country's name! Thanks :') I asked because when a checked CALTECH's website, they recommend 4 years of Maths and some other websites advise you to take Maths, Physics, Bio and Chem all four years. Do all colleges have these requirements? If they're 'recommended' even, does that mean I have a long shot at getting in? Do you know anyone who has been in a similar situation? Finally, Can I apply for a major and then change it next year?