My sister is in 9th grade biology and her teacher avoided answering the question of how we actually study the inside of a cell. I haven't taken biology in a while but I'd like to give her an answer.
Can someone roughly summarize how we actually learn about what goes on inside a cell? Just mentioning a few of the most common or used techniques would be fine.
Note: I hope this isn't a bad question. It's a bit vague. But I didn't want to leave her without a decent answer.