DC has led the country in giving its residents universal access to preschool, and and New York and other cities are now following suit. But if preschool is going to close the achievement gap for low-income kids, it has to be high-quality. And even that may not be enough to do the trick.

A good preschool program teaches all children the social and emotional skills that will help ensure their future success in school: things like how to cooperate with their classmates and how to listen when the teacher is talking.

But research has shown that in the first 4 years of life, high-income children hear about 30 million more words than their low-income peers. So if kids at all income levels are going to start kindergarten on an equal footing, preschools serving poor children need to also provide the vocabulary and background knowledge that wealthier ones get at home.

That’s especially important here in DC, where 3 out of 4 entering 4th-graders read below grade level. Should we now follow the lead of other cities and start even earlier than preschool?

In the District, both DCPS and charter schools offer public preschool. There are about 60 charter schools that offer early childhood education, starting at age 3 or 4, according to the Public Charter School Board (PCSB).

All DCPS elementary schools and K-8 education campuses offer pre-kindergarten for 4-year-olds, and most elementary schools also offer preschool for 3-year-olds. DCPS doesn’t guarantee pre-K or preschool slots at neighborhood schools. Residents have to enter a lottery to secure one.

Which programs work?

Early childhood programs in DC haven’t been evaluated the way K-12 schools have, although the PCSB is working on a system that would do just that for charter schools. DCPS gives preschool children assessments to see how their academic and social skills are developing, but it doesn’t use those results to evaluate the programs.

So it can be hard to know which programs are really helping to level the playing field for poor kids and which aren’t. It would help if DC had a kindergarten readiness assessment in place, which would inventory the skills all students are coming in with. More and more states are adopting such tests, but DC is part of a consortium that is still working on one, according to a spokesperson for the Office of the State Superintendent of Education.

DCPS has pinned its hopes on a curriculum called Tools of the Mind, which is currently used in 70% of its high-poverty preschool classrooms. KIPP DC, a charter school that serves mostly low-income kids, has also begun using the curriculum this year at one of its 4 early childhood campuses.

Both DCPS and KIPP DC are pleased with the program. Melissa Salmanowitz, a DCPS spokesperson, says that DCPS’s assessments show that children who have gone through the Tools curriculum score “significantly higher” on both social-emotional and cognitive assessments.

KIPP DC’s chief academic officer for early childhood education, Laura Bowen, said that she’s been particularly impressed with the teacher training provided by the Tools of the Mind organization. But she also said that the school has supplemented the curriculum with additional elements, as it does with other early childhood curricula it uses.

Studies have concluded that Tools has positive effects on children’s behavior and social skills, but it’s less clear that it’s giving poor kids the leg up they need in other areas. One study found the curriculum had “no discernible effects” on literacy and math skills for low-income preschool children.

Another study, also focusing on low-income children, found that it improved language development, but that the effects were too small to be statistically significant.

Although a small study of Tools recently found some tweaks that appear to help children learning English as a second language, most other research has found no evidence that the curriculum works better than more traditional approaches.

AppleTree’s curriculum

AppleTree Institute for Education Innovation, which conducts research and runs a network of early childhood charter schools in DC, has developed its own curriculum. AppleTree’s CEO, Jack McCarthy, says the curriculum, called Every Child Ready, does a better job than Tools in providing the skills and knowledge that will help narrow the achievement gap.

He cites data showing that 95% of AppleTree students score at or above the normal range on measures of vocabulary and other literacy skills. That reduces the likelihood that they’ll need special education services, as 18% of DCPS students currently do.

Several other charter schools are also using the Every Child Ready curriculum, in a total of 40 classrooms. AppleTree provides them with training and support, just as the Tools of the Mind organization does for schools that use its curriculum.

There are promising signs that Every Child Ready helps boost young children’s literacy skills, but McCarthy concedes that right now there’s no conclusive evidence that Every Child Ready can close the achievement gap between high- and low-income children.

Still, it’s almost certainly true that either early childhood curriculum, when implemented well, will prepare low-income kids for school better than no preschool at all, and also better than a low-quality preschool program would. But is even a high-quality preschool enough to close the achievement gap? Or is it necessary, but not sufficient, to do the job?

One problem is that a child can graduate from a terrific early childhood program and go on to a dysfunctional school. If that happens, the benefits of preschool may be lost. That’s one reason AppleTree has decided to partner with two high-performing charter organizations, Democracy Prep and Rocketship, that will soon be coming to DC. AppleTree will provide the early childhood instruction within the larger schools.

Is preschool too late?

But some cities aren’t waiting until kids are old enough for preschool to begin working on the achievement gap. In Chicago and Providence, programs are underway to visit low-income parents and encourage them to speak more to their infants and toddlers. They also guide parents to interact with their kids differently, giving them more encouragement and asking open-ended questions.

The children are fitted with small electronic devices that record the number of words heard and spoken, as well as the amount of back-and-forth between parents and children.

A program like this obviously costs money, and it won’t necessarily work with all parents. But it’s likely that many low-income parents simply don’t realize the importance of verbal interaction with their children. Getting them to understand that could have effects that last far beyond early childhood.

DC has been out in front in providing universal access to public preschool, and it should be commended for that. But given the size and intractability of our achievement gap, maybe we should now follow the lead of these other cities and try starting even earlier.