Which First Lady continued working as a college English professor while in the White House?

Which First Lady promoted highway beautification and wildflowers? Which former First Lady became a U.S. senator from New York and Secretary of State? Which First Lady launched the "Let's Move!" campaign against childhood obesity? Which First Lady was a former librarian and teacher who promoted literacy? Which First Lady was born in Slovenia? Which First Lady was born in London, the first born outside the U.S.? Which First Lady was both the wife of one president and the mother of another? Barbara Bush was the wife of one president and the mother of which other president?