Mariah Carey and Ex Nick Cannon Honor MLK Jr. Day by Taking Twins Monroe and Moroccan to Museum

Monday was family day for friendly exes Mariah Carey and Nick Cannon.

The former couple proved once again to be masters of co-parenting 6-year-old twins Moroccan and Monroe, using the holiday as an opportunity to teach their kids about Dr. Martin Luther King Jr. during a trip to a museum.

“Celebrating today in honor of the Reverend Dr. Martin Luther King Junior at the Kidspace Children’s Museum,” the 47-year-old singer captioned an Instagram post, adding the hashtags “#Dream” and “#ThankYouDrKing.”

Want all the latest pregnancy and birth announcements, plus celebrity mom blogs? Click here to get those and more in the PEOPLE Babies newsletter.

In the first group shot, they all posed while doing an activity seated at a table. Carey, Cannon and their kids then got silly posing in a photo booth, with Moroccan and Monroe both throwing up peace signs.

Carey and Cannon, who broke up in 2014 after six years of marriage, still spend plenty of time as a family, from fun-filled days at Disneyland to celebrating the twins’ birthdays to coloring eggs for Easter.

In May, their “friendly ex” status caused friends to even wonder if they’d rekindled their relationship.

“Mariah and Nick are getting along great,” the source told PEOPLE at the time. “Nick spends most of his time with Mariah and the kids. Mariah is great with Nick around. There seems to be hope that they will get back together permanently.”

RELATED VIDEO: Nick Cannon and Mariah Carey Attend Kids’ Choice Awards with Twins in Matching Outfits

However, an additional Carey insider told PEOPLE that they were nothing more than pals. “Honestly, they are co-parenting,” said the insider.

Carey and Cannon both rebuffed the rumors in an May 2017 interview with Entertainment Tonight.

“We’re together when it counts,” insisted Carey. “We’re together for the kids. And I think that’s the most important thing.”

For more coverage, follow our babies magazine on Flipboard.

“It’s so perfect right now honestly, I’m working on being the best me that I can possibly be and from that I’m working on being the best father that I can be and that’s a plate full right there,” Cannon, who welcomed son Golden in February 2016 with former Miss Arizona U.S.A. Brittany Bell, echoed. “I love her, I adore her, that’s always going to be my dream girl but I think as mature adults I think we just operate better with the way things are right now.”