When classes let out for the day at Bessie Carmichael Elementary in San Francisco's South of Market neighborhood, Principal Tina Lagdamen high-fives each boy and girl and says the same thing, over and over again: "See you tomorrow."

This seemingly simple phrase is an important reassurance for many of these kids, Lagdamen explains. Roughly 80 families at this school are homeless, which translates to more than 100 children here who are living in shelters, couch-surfing with family and friends, or even sleeping in cars.

"I always say, 'See you tomorrow,' so they know that there's one person they know they can count on that they can see tomorrow," Lagdamen says. "Because sometimes in their lives they have to get up from a shelter or they get evicted."

Most families don't tell Lagdamen right away that they're homeless. She relies on her security guard, Dante Washington, to help her figure out who needs help. The telltale signs usually appear in the morning, when the kids first arrive.

"You can tell when they get to school, they don't really feel great. You know, they're not happy, smiling." Washington says, pausing to greet a small boy who flashes a bright smile. "This is one of my little people right here. When they're not like this in the morning, I can tell something's up."

Fundraiser Focuses on Families

There are nearly 2,000 homeless schoolchildren in San Francisco. Earlier this month, San Francisco Mayor Ed Lee made a bold promise to get most of them -- and their families -- into permanent housing by 2020. To do it, he's asking schools to refer homeless parents to Hamilton Families, a local nonprofit.

Hamilton is in the midst of a $30 million fundraising campaign to expand its signature "rapid rehousing" program. The program attempts to move families out of shelters and into their own homes as quickly as possible through the use of rental subsidies and partnerships with landlords willing to help homeless families find stability.

"The number of families who are entering the system seeking services isn't changing that dramatically now," says Hamilton Families Director of Housing Elizabeth Hewson.

"But there is this backlog of families who've been experiencing homelessness and unstable situations for a long period of time. We believe we can clear the backlog by stepping up our services," she adds.

Housing -- Yes, But Not Near Jobs

The initiative could put people like Ibrahima Bangoura and his 16-year-old son, Mustapha, on a faster track out of homelessness. But staying in -- or near -- San Francisco is more challenging. Bangoura, a single father from Guinea, came to San Francisco six years ago and has been homeless for much of that time.

"It's not easy," Bangoura says in halting English. "It's stressful, not having a house." When Mustapha joined his father in the U.S. in September, they couldn't find a shelter that would take them both. The pair often spent the night at the airport, where they pretended to be stranded travelers.

"Like we are waiting, but not really," Bangoura laughs.

Now, father and son share a bunk bed in a family shelter run by Hamilton. A caseworker is making sure Mustapha gets after-school tutoring while she works with Ibrahima to find a job and permanent housing, preferably in San Francisco.

Finding affordable homes in this pricey city remains no easy feat. In fact, Hamilton is currently placing only about one in five families in the city. The rest are sent to more affordable cities, such as Vallejo and Sacramento.

That's one of the flaws in the city's initiatives, says Coalition on Homelessness Director Jennifer Friedenbach, who worries families who move to San Francisco's suburbs and exurbs will encounter fewer resources to pull themselves out of poverty. "There’s just not the job base we have in San Francisco,” she says.

Indeed, there’s no firm guarantee that families will continue to stay afloat once their subsidies expire -- the $30 million being raised through public and private sources is finite. But right now, the data show Hamilton's model does succeed at getting children into more stable environments.

Hamilton reports that 92 percent of the families they house are still in their homes a year after their subsidies end.

"There is no perfect solution in the Bay Area with our housing market," says Hewson, adding that Hamilton is making the most out of limited resources. And for this fundraising campaign, private companies, faith communities and private philanthropists seem eager to answer the mayor's call to house homeless families now.

The fundraising is already more than two-thirds of the way there, with big-name donors that include philanthropists Marc and Lynne Benioff, Salesforce, Google and the San Francisco Giants.