Brooklyn Williams, a second-grader at Walker-Jones Education Campus, tries to pick up some cycling techniques from her classmates. (Linda Davidson/The Washington Post)

Second-grade students at Walker-Jones Education Campus this week are learning a new alphabet: The ABC’s of bike safety.

“Air! Brakes! Chains!” they yelled to “Mr. G,” their physical education teacher, after he showed them how to inspect their bicycles for potential problems.

Dressed in orange vests and bright blue helmets, the students climbed onto Diamondback Mini Viper BMX bicycles and began to pedal. Some careered around a course set up in the gymnasium. Others did not get past the starting line.

“I’ve tried three wheels before, but not two,” said Vicky Zou, 7. “I’m a little nervous.”

The students are among the first to take part in a new D.C. Public Schools program to teach every second-grader how to ride a bicycle. The school system, with help from the District Department of Transportation and private donors, purchased 1,000 bikes that will rotate to every elementary school by the end of the school year.

Second-graders listen as physical education teacher David Gesualdi goes over how to put on a bicycle helmet. (Linda Davidson/The Washington Post)

The bike-riding unit is one of the District’s new “cornerstone” lessons, which aim to bring more uniform and rigorous instruction to students in every part of the city. They are designed to be memorable and relevant learning experiences, said Brian Pick, chief of teaching and learning for D.C. Public Schools.

The unit also reflects efforts across the country to make physical education classes more accessible and useful, with less focus on competitive sports and more attention to healthy lifestyles and fitness habits.

“This a lifelong skill,” said Miriam Kenyon, director of health and physical education for D.C. Public Schools. “It’s a way students can get to school and it’s also a way they can exercise with their family. It promotes independence, and it’s a good way to get around.”

Kenyon said the District wants to make sure that students in all parts of the city know how to ride a bike, a skill that many people take for granted. In wards 7 and 8, with high concentrations of low-income families, officials are concerned that less access to bicycles, fewer bike lanes and no bike shops means that fewer children there are learning how to ride.

That concern comes as bicycle riding in the District and its suburbs is growing quickly, with a rapid expansion in popularity of bike sharing and miles of new bike lanes installed in recent years.

About 4 percent of D.C. residents commuted to work by bicycle in 2014, compared with fewer than 1 percent in 2000, according to census data. That puts the District well above the national average and in the top five cities nationally. Larger numbers of commuters are concentrated in wards 1, 2, and 6, which are in central and relatively affluent parts of the city.

Bike advocates note that the infrastructure for cycling east of the Anacostia River is less developed. Capital Bikeshare, the popular program with 30,000 members in the region, said a survey showed that more than 80 percent of its members are white, 63 percent are younger than 35, and 59 percent are male, according to self-reported data.

Daniel Hoagland, an education coordinator at the Washington Area Bicyclist Association who has taught bike safety courses in D.C. schools in recent years, said he encountered “surprisingly high numbers of kids” who did not know how to ride, especially in schools serving poor neighborhoods.

He also teaches adults to ride and has heard various reasons why people don’t learn as children. Some had a bad experience early that caused them to abandon the effort, and some come from other countries where bike riding is not common or easy to do. Many said their parents did not know how and never taught them.

“My friends know how to do it, but I don’t know how,” said 7-year-old Lachae Taylor as she began to learn at Walker-Jones on Wednesday. After a few minutes of wobbling, her helmet was pitched to the side of her head and both shoelaces on her sparkly high-tops were untied. Every time she lifted them to the pedals, the bike tilted to one side.

“I wish I had training wheels,” she said.

D.C. school officials said they chose to introduce the skill in second grade, in part because the curriculum emphasizes coordination and balance. It’s also an age at which children aren’t afraid to fall, Kenyon said, and at which enough students already have learned and can help teach their classmates.

“We decided second grade is a foundational year,” said David Gesualdi, a physical education teacher at Walker-Jones. “A kid needs this experience before second grade, and if they don’t receive it by this age, we are going to provide it.”

The students learn bicycle safety, including how to wear a helmet, how to use hand signals and other rules for riding safely on city streets or paths.

Many school systems in the Washington region teach bicycle safety as part of their health and physical education curriculum, and some teach students to ride. Fairfax County offers optional lessons for older elementary students, and Arlington County offers lessons to some high school students.

In the District, the unit is four weeks long. The classes meet only once a week for about 50 minutes, but Gesualdi said he hopes to extend the unit by a week or two and plans to make the bikes accessible at other times for students who want to practice. At the culmination of the course, he is planning a six-mile ride around the city.

Tyliah Rogers, 8, said she already feels confident on the bike.

“My grandmother taught me,” she said. “She said, ‘Just hold the bars, do the pedals, and keep on going!’ ”