Hillary Clinton took a very special "study break" before the presidential debate

By Tierney McAfee
September 28, 2016 05:40 PM
Jon Davidson, Office of President Clinton

Monday was a big day for Hillary Clinton – and not just because it marked the first 2016 presidential debate, but also because it was her granddaughter Charlotte‘s second birthday.

Between debate prep sessions on Sunday, Clinton took time out for a “study break,” to attend little Charlotte’s kiddie birthday party at Apple Seeds indoor playground in New York City.

A source familiar with the party tells PEOPLE Clinton spent hours at the event and that “she was really happy, and really present and really there. She wasn’t working.”

Adds the source, “She’s this super-present grandmother and mother and even before the night of the debate, she was showing her support for her family … She prioritizes that, hands down.”

Sunday’s celebration featured typical things you would find at a children’s birthday party – balloons, pizza and cake – with the added bonus of a live three-piece band from Songs for Seeds, a music education program for young children launched by the founders of Apple Seeds. Chelsea Clinton‘s daughter also takes Songs for Seeds classes, in which the band plays rock music to teach children about animals, shapes, colors and numbers. The Clintons “love the class,” says the source.

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The Democratic nominee has said that becoming a grandmother transformed her.

In a joint interview earlier this year with her daughter, Chelsea – who also 3-month-old son named Aidan – Clinton said, “Watching Chelsea mother Charlotte is just the greatest joy.”