First Lady Michelle Obama traveled across the Anacostia River on Friday to Orr Elementary, where she urged educators in the District and across the country to keep pushing for healthy food and more physical activity in schools.

America’s campaign against childhood obesity is ushering in a “cultural shift” that’s beginning to make a difference, Obama said. But there’s still a long way to go, she added — and schools must take a lead role in helping kids build good habits.

“We’re currently on track to raising the most inactive generation in our nation’s history,” Obama said. “And it’s time for us to do something about it, starting right now.”

Flanked by D.C. Schools Chancellor Kaya Henderson and retired pro basketball star Shaquille O’Neal (“one of the few people on Earth who can make me feel small”), Obama called on educators to commit to her “Let’s Move! Active Schools” program and to offer at least 60 minutes of physical activity each day — before, during or after school.

“As educators, you play such a pivotal role in this effort,” she said. “We have the potential to transform the health of an entire generation of young people.”

Two other sports stars also joined the group: Olympic gymnast Dominique Dawes and Olympic sprinter Allyson Felix.

Henderson announced that all 111 D.C. traditional schools have signed up for Obama’s program, making the District the first school system in the nation to go “all in for this exciting and empowering program.”

Obama’s visit and Henderson’s commitment came on the heels of parents’ protest that the D.C. school system — which cut the minimum requirement for recess this year to 15 minutes a day — does not devote enough time to exercise. Officials decided last week to raise the minimum to 20 minutes — still too little, in many parents’ eyes.

“There’s not enough time in the day to fit in everything,” said spokeswoman Melissa Salmanowitz, adding that the backlash over recess shows that the schools need longer than their current 6.5-hour day. “But we’re fully committed to providing physical activity before, during and after school.”

Orr Elementary, where poverty is so pervasive that all the students qualify for free and reduced-price meals, is one school that has made an effort to ensure that kids are eating well and moving during the day.

“I know play is important,” said Principal Nikeya Wilson, who is new to Orr and tried to schedule the school’s 20-minute recess to fall after students’ language-arts block and before math.

“Students are more engaged after they’ve had time to get their wiggles out,” she said.

Vending machines are stocked with healthy snacks, and every morning, the school offers a free exercise program called “BOKS,” designed by the athletic company Reebok. Dozens of Orr students crowded into the school’s multi-purpose room to share a BOKS session with Obama and O’Neal.

“You guys are leaders. You guys are an example for the whole country,” Obama told the students, who were squealing and jumping and clapping their hands over their mouths in excitement. She urged them to stay active, eat their vegetables and take school seriously.

“When I was your age, I never missed a day of school,” Obama said.

“Whoa!” said one impressed little boy.

The children jogged and skipped and cajoled hugs out of the first lady. They leapt as high as they could in an effort to high-five seven-foot-one O’Neal. Some succeeded. Others whiffed.

O’Neal, who was promoting Reebok’s effort to expand BOKS to schools around the country, said he hadn’t realized how important schools are for kids’ exercise until he went to Miami and met parents who were scared to let their children outside in violence-wracked neighborhoods.

“I was blind to the issues,” he said. “We have to come up with more, smarter ways to keep kids active in school.”