A new study shows large literacy gains and other benefits for full-day preschoolers as they enter kindergarten compared with their half-day peers — timely findings given the surge of new publicly funded preschool classrooms in Colorado.

The new evidence, gleaned from a study of students in the Westminster school district north of Denver, comes amid the rollout of two major early childhood initiatives championed by Gov. Jared Polis. They include the launch of free full-day kindergarten statewide and the expansion of free state-funded preschool for students with certain risk factors.

The preschool expansion, rolling out this fall and winter, has allowed school districts across the state, including Westminster, Denver, Aurora, and Englewood, to create new full-day preschool seats. District officials say many parents want the full-day option because it aligns better with their work schedules. Plus, they say the longer day gives youngsters additional time to learn important social, emotional, and pre-academic skills.

Now there’s homegrown research using gold-standard methodology to support the shift.

“From a research perspective what is so exciting here is it’s the first experimental evidence on full vs. half-day pre-K,” said Allison Atteberry, a University of Colorado Boulder researcher who co-authored the study with two researchers from the University of Virginia.

Atteberry and her colleagues were able to isolate the effects of the full-day program by comparing Westminster preschoolers who won a spot in a full-day classroom with those who lost the random lottery to get in.

Atteberry said previous research on the topic suffered from the “correlation is not causation” problem. In other words, what might have appeared to be positive effects from full-day preschool couldn’t be definitively tied to the longer day.

While the new study examined one small program serving around 200 students, and can’t say whether the benefits would apply elsewhere, the results are good news for early childhood advocates.

The study came out of a pilot program launched by the 9,300-student Westminster district in 2016. District leaders wanted to test a novel financing mechanism for full-day preschool, building a rigorous third-party evaluation into the project.

The district, where 80% of students qualify for government subsidized meals — a measure of poverty — relied on philanthropic dollars to launch its new full-day preschool classrooms. Little state money was available for full-day seats at the time, and Polis’ election as governor — and his ambitious early childhood agenda — was still two years away.

Mat Aubuchon, Westminster’s director of elementary education, said Colorado’s early childhood landscape has shifted so much in the past few years, that the financing mechanism originally being tested — called Pay For Success — is no longer a critical piece of the funding puzzle.

But the new evidence on full-day preschool outcomes is important, he said. “We’ve always thought full-day preschool was helpful … but the study was able to authenticate that.”

The study released this month focuses on the 226 students who attended full and half-day preschool during the 2016-17 school year. Researchers are also tracking two additional sets of Westminster preschoolers — those who attended in 2017-18 and 2018-19.

Aubuchon cautioned that since researchers plan to track all three sets of preschoolers through at least third grade to see if the early gains fade out or not, “we have a long way to go.”

Prior research in Tennessee found that initial preschool gains can disappear within a couple years, especially if students don’t have effective teachers in elementary school.

The new study found that full-day preschoolers had significantly better scores on tests of receptive vocabulary — the set of words they understand and can apply to the world around them.

Atteberry said such vocabulary skills represent a key building block of literacy, the foundation for learning in all subjects.

Full-day preschoolers also received higher scores than their half-day peers, on two other assessments: an early literacy assessment and a broader assessment that examines a range of areas, from social and emotional skills and physical development to math and literacy.

For many early childhood leaders, the latest study affirms what earlier studies and their own experience have long suggested.

“We know the value of improving student outcomes with full-day programming is real,” said Suzanne Rougier, director of early childhood education for the Aurora district.

But Colorado historically hasn’t allowed for many full-day preschool seats through its taxpayer funded preschool program, which serves mostly 4-year-olds and a small number of 3-year-olds. It’s available to children who come from low-income families, have lagging language development, poor social skills, or other risk factors. Only about 9% of 27,000 students in the program attended full-day preschool in 2017-18.

But this year, the state offered up 5,000 new half-day slots, which many districts are combining to create new full-day slots.

Aurora, which previously had only two district-run full-day classrooms, got enough new funding from the state to create five new full-day preschool classrooms in August. It will add four more in January.

“The ask from parents is always about full-day. We know the need is out there,” Rougier said. “When this opportunity came up, we didn’t even look at half-day.”

The Westminster district used new preschool funding from the state expansion to create five new full-day classrooms this year, plus sustain nine others that had been funded previously by local foundations as part of the study.

Aubuchon said three-quarters of district preschoolers now attend full-day classes.

In the 2,600-student Englewood district south of Denver, a gleaming new preschool center opened last January, jumpstarting the shift to majority full-day programming. This fall, the district added another full-day classrooms thanks to the new state funds, for a total of nine full-day classrooms.

All told, about 60% of Englewood preschoolers attend full-day classes this year, and district leaders plan to add two more full-day classrooms over the next two years.

Leigh Pytlinski, the district’s director of early childhood education, said she doesn’t see the district eliminating half-day preschool entirely because some children have wonderful care at home or with relatives the other half of the day.

But many full-day preschool students tend to be more mature and independent when they start kindergarten, she said, better at tasks like hand-washing, putting their dishes away after eating, and solving problems that crop up during play. They also get more time for lessons — or post-lesson activities — on math and science topics, cooking, and music.

Half-day students get a taste of those opportunities too, Pytlinski said. “They are just more rushed because we’re trying to cram them into three hours and 15 minutes.”