So now we know that a law is like a rule that we must follow. We know that Congress makes the laws, and now we will learn how they are made.

Laws start in Congress. When someone in the House of Representatives or the Senate wants to make a law, they start by writing a bill. A bill is like an early version, or a draft, of the proposed law.

Each Congress lasts about two years. During that time, Senators and Representatives may introduce thousands of bills. Yet only some of those bills will eventually become laws.

The bill has to be voted on by both houses of Congress: the House of Representatives and the Senate. If they both vote for the bill to become a law, the bill is sent to the President of the United States. He or she can choose whether or not to sign the bill. If the President signs the bill, it becomes a law. If the President decides not to sign the bill into law, it is called a veto and the bill is sent back to Congress. Congress can bypass, or override, the veto with a two-thirds vote in both the House and the Senate. The bill would then become a law.

Lesson Plan from the American Association of School Librarians:
How Laws are Made—Ben's Guide