Answer: Amendments must be ratified by the states. They do not become law with the signature of the President.
Step-by-step explanation:
Bills passed by Congress become law with the signature of the President. Amendments to the Constitution, however, require a more stringent process.
An amendment must first be approved by Congress and then also must be ratified by the states. An amendment must be approved by a two-thirds vote in both houses of Congress, and then three-fourths of state legislatures then must ratify the amendment in order for it to become a part of the federal Constitution.