When the weather’s nice enough, students at Cesar Chavez Public Charter Schools for Public Policy’s Prep Campus in Washington’s Columbia Heights neighborhood walk single-file up Kenyon Avenue through a narrow alleyway into the Bruce Monroe Community Park — a public park — for recess.

On other days, the sixth- through ninth-grade students are sent to the teacher’s parking lot next to the school, where they run sprints. Without a gymnasium, the school’s teachers are forced to improvise activities for the more than 300 students in a limited space. In bad weather, they use a small basement classroom to watch documentaries about nutrition, play board games, or do yoga. Students in after-school sports are bussed off-campus to practice or for games.

The school recently embarked on a $2.2 million dollar campaign to build a gym over the parking lot next to the school, funded by philanthropists, government grants, and charitable foundations, tentatively scheduled to finish by the end of the calendar year. In one of the first examples of a public charter school using crowdfunding, Cesar Chavez staff hoped to supplement traditional funding with small contributions from large groups of individuals, to raise an additional $30,000.

Ultimately, though, the campaign reached a little more than a third of its goal, illustrating some of the challenges of crowdfunding social ventures.

Crowdfunding is a phenomenon relatively new to the education world, crowdfunding analyst Chris Camillo said, and the few school systems using the method are still developing the social media savvy required for a successful campaign. But the transparency of a crowdfunding campaign — in which the school defines for donors online exactly how the funds will be used — contrast the more traditional method of making general donations to a school or a fund, he said.

“It’s really easy to do a bake-sale,” Camillo said. More challenging is “forcing students and teachers to organize a business plan, to put together an effective crowdfunding campaign, making a pitch.”

Christine Lai, marketing manager for the Cesar Chavez schools, ran the crowdfunding campaign with two colleagues. About a month and a half ago, she created a Web page for the cause on StartSomeGood, a D.C.-based online crowdfunding platform for non-profits and social entrepreneurs. Once projects on StartSomeGood reach a certain “tipping point” chosen by the entrepreneur — between 25 and 100 percent of the goal — they can keep the funds they raise, and the platform only takes a cut of funds raised if the campaign meets its funding goal.

Alex Budak founded the platform two years ago in D.C., after a stint in India teaching girls from slums to play Ultimate Frisbee. “I had this realization that fundamental social change isn’t going to come from one or two huge organizations, but rather, it’s going to come from lots of people pursuing their own version of social good,” Budak said.

When he returned to the U.S., Budak wanted to start his own social enterprise for sports and youth development. “The more I thought about it, the more I realized I didn’t really didn’t know how to get started, how to get that initial capital I needed to get off the ground and how to get that initial group of supporters to be there to help me. I realized, ‘Hey, if I don’t know how to take action on this idea, how many other great ideas must there be, that could never go from the idea state to actually taking action on it?’ ”

Since its founding, the platform has helped 142 projects secure funding, about 60 percent of the projects on the site. The average campaign is for about $5,000, but range from a few hundred dollars to hundreds of thousands.

Lai and her team spent 10 hours a week managing the campaign, e-mailing the school’s contacts and personal connections and handing out promotional fliers. They tweeted to @ChavezSchools’ more than 600 followers, originating the hashtag #PlayItForwardDC, and using #WeightLoss or #HealthyKids and linking to the campaign. Perks given in exchange for contributions included regular updates about the gym’s progress for smaller donors, or hard-hat tours of the completed gym for larger ones.

Sometimes, Lai tweeted the student’s fitness goals, hoping to personalize the cause for potential contributors.

“My goal = lose 20 pounds by playing #basketball.” -Alexander #8thGrade #ChavezPrep #WeightLoss http://bit.ly/11fa3jX #PlayItForwardDC,” @ChavezSchools tweeted in April.

By the beginning of April, the campaign had reached its tipping point — $7,500, meaning the school would keep that and whatever other funds it raised.

In an effort to earn publicity, Lai also tweeted a link to the campaign at big names like Nike, which has more than a million followers, or singer Justin Timberlake, who has more than 20 million, hoping they’d retweet it. Though neither Nike nor Timberlake responded, Lai said the campaign saw a small bump in traffic after users searching for those accounts stumbled upon the tweet.

But by its end date in May, the campaign had only raised $11,179 from 108 supporters, many of whom had personal connections to the school through the students or faculty, Lai said. The most popular donation size was around $50, and the largest donation was around $2,500.

“Overall, we’re a little bummed in terms of not reaching our goal,” she said, but noted the school is continuing the funding search, and that the gym is still in progress. In future crowdfunding campaigns, Lai said she’d spend more time publicizinsg it, which would require more careful preliminary planning to identify big-name supporters.

“But often, nonprofits in education are stretched so thin,” she said. “Being able to have more internal support, to have more people on board, and more time and planning” could have helped them meet their goal, she thinks.

The students were monitoring the campaign closely, Lai said, but even though it didn’t meet its goal, “they’re not disappointed. They knew it was a big reach for us. We’re not going to raise $20,000 in a day.”