[balabaster]

That's because in high school you're not really given the whole picture of how to apply your knowledge and you don't have the life experience yet to understand how to use it usefully so while you understand the math in a limited fashion, you don't really get it. By the time you're in College, you're expected to really get it by the time you sit down in an exam and can apply it to the real world. So the exam questions are designed to test if you really do get it or if you're just going through the motions of what you were taught.