By Katia Hetter, CNN
Updated 11:14 AM ET, Friday, April 1, 2016
When Ken Burns' daughters were little, they played a game of memorizing the names of the presidents at bedtime.
"George?" he'd say.
"Washington!" Sarah would say, followed years later by Lilly, Olivia and lastly, Willa.
"Grover?"
"Cleveland!" his daughters would reply for the 22nd president of the United States.
Then would come the 23rd president, Benjamin Harrison, followed by "Grover?" again.
"Grover Cleveland, again!" they'd say, giggling, for the only president to serve two nonconsecutive terms.
As each daughter memorized the names of the presidents, always giggling at the 24th president's name, "I'd say 'Let's do a children's book' " about the presidents, Burns told CNN.
In the meantime, Burns made stunning documentaries about the national parks, the Civil War, the Roosevelts and baseball that brought history to life on our television screens.
Thomas Jefferson, Abraham Lincoln, Theodore Roosevelt and Franklin Delano Roosevelt all featured prominently in his work, and he's met six presidents: Jimmy Carter, Ronald Reagan, George H.W. Bush, Bill Clinton, George W. Bush and Barack Obama.
"I'm one of those nerds of the history of the United States," Burns said. "I may be American history's biggest fan."