Although vocabulary lists and flash cards may assist you in preparing for a test, if you intend to focus your studying to what the teacher thinks is important, a good idea would be to look at past papers (which can include tests that have been written before or quizzes) and your own notes.
When a teacher teaches a certain topic, they usually focus and explain the parts of that topic that they want people to understand, and if they specifically want people to understand one certain section, there is a high chance that they will put that topic in the test.
Black holes are great amounts of matter packed into a small space. When massive stars collapse upon themselves. When stars aren't able to fuel themselves they become compact. Which turn into black holes.
