Sometimes the word man or mankind is used when referring to all human beings (both male and female):
Throughout history, man has worshipped gods or spirits.
The universe will never be completely understood by mankind.
However, some people consider this sexist, so it is better to use humans or humankind:
Throughout history, humankind has worshipped gods or spirits.
The universe will never be completely understood by humankind.
Humans first migrated to the Americas 15,000 years ago.
This spider's venom is deadly to insects, but harmless to human beings.
Humans and human beings use the plural form of the verb, but humankind uses the singular form of the verb:
humankind has worshipped gods
humans have worshipped gods
We often use humans or humankind when making broad statements about humanity in general. Human beings is often used when contrasting humans with animals, or when encouraging people to treat each other "like human beings" (meaning with respect and fairness).
Obviously, before you can review your notes you must first have notes. Always make sure to take good notes in class. Before you start each study session and before you start a particular assignment review your notes thoroughly to make sure you know how to complete the assignment correctly.