Fresh off the campaign trail, the freshman class of the 113th Congress came to Washington two months ago for the crash course that is New Member Orientation.

Though weighed down physically by stacks of papers and mentally by facts and figures, they were almost giddy, wide-eyed and willing to speak about anything with a reporter.

On Thursday, back in Washington to be sworn in to office, many of these new lawmakers were still enjoying the whirlwind of being in Congress — even as returning members were catching up on sleep after a demoralizing sprint to the finish of the 112th Congress to wrap up a deal on the fiscal cliff.

Not yet officially a member of Congress on Thursday morning, Rep. Patrick Murphy, D-Fla., rifled through his manila envelope of member goodies in the Speaker’s Lobby like he was opening a present. Inside were the standard issue voting card, congressional license plate and picture ID. There was also a set of pins to wear, one for lawmakers and one for their spouses.

“I don’t have a spouse; I guess I can just give this to anyone,” Murphy said with a laugh.

Nearby, a staffer was explaining all the paraphernalia to a somewhat perplexed Rep. Andy Barr, R-Ky. Rep. Gloria Negrete McLeod, D-Calif., struggled with how to place her broach and member’s pin in symmetry on either lapel of her suit jacket, and she and an aide disagreed over which was the voting card.

Friendships were also being formed between lawmakers new and old.

During the group swearing-in ceremony and leadership elections on the House floor, new Rep. Sean Patrick Maloney, D-N.Y., sat beside veteran Congressman Tim Walz, D-Minn. Maloney’s two young children played with Walz’s children.

The lawmakers, with help from the youngsters, later explained that they all had met the day before when Walz’s wife was paired up with Maloney’s partner as part of a congressional spouse mentoring program.

While the House floor was a buzzing, chaotic scene during the swearing-in ceremony, the Senate was a relatively serene affair, with Vice President Joseph R. Biden Jr. swearing in new members and welcoming them with firm handshakes and pats on the shoulder.

Sen. Christopher S. Murphy, D-Conn., provided the day’s YouTube-worthy moment at his mock swearing-in ceremony in the Old Senate Chamber. As Murphy raised his hand to re-enact the oath, his son Rider nestled in his left arm and raised his arm as well. “What a picture that’s going to be,” Biden said.

Biden also provided some comic relief when, while posing for photos with North Dakota Democratic Sen. Heidi Heitkamp and her family, he told Heitkamp’s husband, Darwin Lange, to “spread your legs, you’re going to be frisked.” After the photo, Biden told Lange, “I’m a little too formal, I know.”

Later on in the day, frazzled freshman Rep. Beto O’Rourke, D-Texas, was picking up M&M’s off the marble floors outside the House chamber to put back in the hands of his 2-year-old son, Henry, who was clearly restless after hours of having to sit still.

“This is the cleanest floor in Washington,” O’Rourke joked, saying his biggest adventure of the day so far was a trip to the snack bar of the Democratic Cloakroom.

Seeing that O’Rourke was struggling to keep Henry and his two other children on their best behavior, a nearby Rep. Loretta Sanchez, D-Calif., took everyone for a quick ice cream sandwich break. O’Rourke proudly displayed a photo of the side trip.

But amid the excitement and the adrenaline of joining the “people’s house,” the freshmen all exuded a sense of purpose. They suddenly had the titles “congressman” and “congresswoman.”

“I’m ready to get to work” was the refrain of new members including Kerry Bentivolio, R-Mich., and Joyce Beatty, D-Ohio.

Elsewhere, Rep. Roger Williams, R-Texas, was walking alone, carrying a leather-bound Bible engraved with his name — a gift from his chief of staff after his election to Congress in November. He explained that he planned to carry it with him whenever he comes to the House floor. It will give him “spiritual strength,” he said.

Jason Dick contributed to this report.

An earlier version of this article incorrectly stated that Rep. Tim Walz was accompanied by his grandchildren on the opening day of the 113th Congress. They are actually his children.