What provision was included in the US Constitution to allow it to adapt to changing times?

The Elastic Clause, also known as the Necessary and Proper Clause allows congress to pass any law "necessary and proper" for the greater good of the people.

Another thing that is used is the Ammendment Process in which an amendment is proposed in congress and voted on by all state legislatures. If three-fourths of those state legislatures approve of it, it is then ratified into the constitution.

I just answered this on my U.S. History Homework. Hope this helps!