Homework

Teachers often give assignments consisting of reading, problem solving or writing that the students must do after class--typically at home. Ideally, the purpose of homework is to help reinforce what was taught in class. Sometimes it is gathering extra information beyond what was taught in class. Unfortunately, there are some teachers that don't understand the meaning of homework and give it as something to keep the students busy.

Reinforce Knowledge: The teacher can provide information and explain the subject in class. The problem is that you typically will only remember 50% of the information you get by seeing and hearing explanations. Also, you may not completely understand the principles or facts involved. You need to apply that knowledge to really learn the subject.
For example, the teacher may explain how to solve a certain type of math problem in class. But unless you go home and solve a couple of problems yourself, you probably won't really learn or understand the method involved. By the next day, you may have already forgotten what was taught. Likewise, your teacher may explain the reasons for the action of people in an historical event. When you read about the event, you will then pick up on what really happened and why.

Beyond Classwork: Sometimes teachers will only give an overview of material and assign reading to get the major part of the information. Then the next day, the teacher may answer any questions students may have or perhaps verbally quiz them on the material. History, English Literature and Sociology are examples of classes that require extensive reading outside of class.
The advantage of this is that much more material can be covered than what could be covered in class. The disadvantage to the student is that often questions aren't answered and there is no reinforcement to enhance remembering what was read. If the homework includes writing essays or answering questions in the book on what was read, there is a degree of reinforcement. You need to apply what you have just read, and often that will help you remember and understand the material. Unfortunately, the only way to find out if you understood the material is if your homework is graded. But that doesn't explain it to you.

Meaningless Homework: The worst type of homework is the type that is meaningless or just "busy-work". It is common for a teacher assign students to look up some subject on the Internet and put together an essay on it. Many will find a number of resources and copy and paste the material without really reading or understanding it. All this amounts to is an exercise in using Google to find things. Another type of homework is doing repetitive problems or solving puzzles that really don't add to your knowledge. Unfortunately, you may have to do this sort of nonsense to get a good grade in the class.

The purpose of homework is to help you learn what was taught in class or to gain information by reading and answering questions. One type is reinforcing what was taught in class, another type is studying beyond what was explained in class, and the third type is primarily meant to keep the students busy. In any case, it is necessary to do your homework--and do it well--to get a good grade in the class.