With a classroom full of squirming 3-year-olds, Kristal Torres at P.S. 277 in the Bronx keeps morning routines short. On a recent fall day, her class started out seated on a rug and singing a welcome tune that called children by name. But within five minutes, they were up and jumping to an upbeat version of the ABCs.

Upstairs, the students in Margie Cruz’s pre-K class of mostly 4-year-olds were sitting patiently around their teacher. They waited as long as 15 minutes for their turn to pick a play center, describing their choice to Cruz before heading off to dig in sand, stack blocks, or cook a pretend meal in a pint-sized kitchen.

New York City has been lauded for its rapid of expansion of free pre-K for 4-year-olds, and now Mayor Bill de Blasio is pushing to expand his signature education effort for even younger students through the city’s 3-K for All program. But as schools welcome 3-year-olds, experts say that serving these children well isn’t as simple as duplicating what’s already in place for older students.

Schools must adapt to reflect the difference a year can make in the lives of 3 and 4 year olds — in attention spans, behaviors, and expectations for the city’s youngest students. Experts warn that failing to recognize those differences could get in the way of deeper learning, or even create behavior challenges if teachers don’t recognize what’s developmentally appropriate as children grow.  

“We really want to make sure that we’re focusing on the 3-year-olds being allowed to be 3,” said Nikki Darling-Kuria, who trains early education providers with the non-profit Zero to Three. “We really have to make sure we get it right.”

The city is moving much more slowly to make 3-K available to all families, partially due to the more than $1 billion price tag attached to the effort and the challenge of finding appropriate space for all those children. This year, about 5,000 students enrolled in the six districts that offer 3-K, and the city aims to expand to a dozen districts by fall 2021. By comparison, about 70,000 4-year-olds are enrolled in the city’s pre-K.

P.S. 277 is among the schools that have expanded its pre-K to include four classes of 3-year-olds this year — double from when the program first started in the 2017-2018 school year. Principal Natasha Bracey’s first task was hiring teachers who would provide the nurturing environment that’s critical for very young learners. The next was taking a look at instruction, including curriculum, to make sure each year of early education prepares students for the next.

“In 3-K, they’re just exploring,” Bracey said. “When they leave pre-K, the expectation is that they’re ready now for the learning that will occur in kindergarten.”

The education department is also focused on adapting instruction for 3-K students, with lessons that encourage children to learn through play and an emphasis on catering to students’ abilities, no matter their age, said Stepha Krynytzky, a senior director in the city’s early childhood education division.

The city allows early education classrooms to use any “research based, developmentally appropriate” curriculum. The city’s own materials cover the same topics and skills from one year to the next, using federal Head Start guidelines as a framework for 3-K instruction, and the state’s own pre-K Common Core standards for 4-year-olds. Instructional coordinators visit classrooms to help teachers tailor their practice to each age group by modeling lessons, providing resources, or leading training sessions.   

“We talk about curriculum in any two grades as being a spiral, where you’re going deeper or higher,” Krynytzky said. “The 3s curriculum in more open ended and exploratory, and the 4s is pushing them deeper.”

A large part of the curriculum for both age groups is, of course, play. But what that looks like can vary widely from one age to the next.

Three-year-olds, for example, aren’t expected to share as they are still learning to become more independent and name their own feelings. Instead, younger students are more likely to engage in “parallel play,” using the same kinds of toys side-by-side with their peers.

In the classroom, that can mean stocking duplicates of materials like the books that Torres laid out that morning. Students picked their own books to flip through while the teacher hovered, pointing out animals they might not yet recognize and asking questions about what they saw.

The older students in Cruz’s classroom, by contrast, waited to take turns using a bottle of pink paint. One girl smiled as another made blots across her paper. At a nearby bin full of soft, white sand, two students worked together to dig a hole. In a classroom of 4-year-olds like this one, you’re likely to see more cooperation with peers, as students take on family roles, say, playing together in a pretend kitchen.

In a classroom of 3-year-olds, a teacher may be more likely to stay in one place — a practice called “grounding” that allows little ones to quickly find a caring adult. Teachers with older students, Krynytzky said, may engage more actively in playtime, assigning each child a different role or even taking on one themselves. Conversations between children and adults might sound different, with more open-ended questions and more elaboration, rather than repetition, of what the student has said.

One of the most obvious distinctions between children who are so small doesn’t have much to do with what many would consider instruction. Rather, 3-year-olds simply need more support taking care of themselves, from washing their hands to buttoning their coats. Three-year-olds are also much more likely to need help with potty training — especially because children can be as young as 2 when they enroll in the city’s program.

None of these differences between age groups are hard and fast, leading some educators to wonder whether separating children into classes by age is even best.

“The idea that all children need the exact same thing at the exact same time is just wrong,” said Ellen Frede, senior co-director at the National Institute for Early Education Research at Rutgers University. 

Frede helped oversee early childhood efforts in New Jersey as the state expanded its lauded pre-K program in the early 2000s. At the time, mixing students of different ages, much like Montessori programs do, was often considered the best approach.

Older students can serve as role models and may require less individual attention than a roomful of the youngest children, she said. The approach has some high-profile backing: Jeff Bezos, the founder of Amazon, who recently announced his company would be opening a new office in Long Island City, has pledged $2 billion to advance Montessori early childhood initiatives.

There are often structural reasons, however, for separating classrooms by age, including how programs are funded or evaluated for effectiveness. In New York City, classrooms are divided partly because the city’s health department requires different staffing ratios by age.

Mixed age or not, the impact of pre-K often comes down to quality curriculum, and teachers who can use the materials well while meeting the different needs of students.

“It’s important that you’re teaching individual children — not a group,” Frede said.

In the push to prepare students for kindergarten, it can be tempting to focus on teaching discrete content, such as recognizing letters, Frede said, to the detriment of developing skills such as language, reasoning, and self-regulation.

“It’s the difference between content, and understanding content more deeply,” she said.

Plus, pushing academic or even social skills before children are ready can pose challenges when children aren’t taught to manage their emotions, or are expected to do things like share before they’re ready. When teachers aren’t trained to recognize what’s appropriate behavior and how to respond, students are often expelled, said Darling-Kuria, of Zero to Three. Expulsion rates in pre-K are three times higher across the country than rates in K-12. (New York City bans suspensions and expulsions in public pre-K programs, according to the education department.)

To avoid those types of challenges, she said the city should take care to treat the city’s youngest learners not like rising kindergartners, but like “2-year-olds with training.”

If we’re making anybody do something that they’re not developmentally able to do, it can create problems,” she said. “You can’t practice being 5 when you’re 3.”