It's been this way for a long time, but some say that free public school should start at age 4.

Universal Pre-K. Free or cheap education for 4-year-olds is already a reality in many wealthy countries around the world. But in the U.S., universal pre-k is often seen as a lofty, progressive goal with a big price tag. And it only exists in a few states and some cities.

Vermont's had it since 2014. So has New York City. And D.C.'s popular UPK program started in 2008. But the U.S. state with the longest continuously running, free, universally available, high-quality education program for 4-year-olds is Oklahoma. Yep, Oklahoma is about as conservative as it gets. It hasn't voted for a Democratic president in 60 years. But this state made free, high-quality pre-k the new normal back in 1998, years ahead of its progressive peers.

Kindergarten is just an arbitrary line. It's hard to even think of us not having pre-k programs. It seems like they've been here forever.

I wanted to know a couple things. How they pulled this off.

The voters didn't have a clue what we were doing, on purpose.

What other states can learn from the program, and what free pre-k looks like a generation of kids later? Now, free pre-k isn't exactly rare in the U.S. Most U.S. states offer some form of state-funded pre-k for 4-year-olds. But very few are considered universal. The majority of these programs prioritize low-income and at-risk children. Programs like that are often part of

Head Start, a big, federally-funded school program that's been subsidizing education for young children living in poverty since the 1960s. A program that the Trump administration is threatening to dismantle. In Oklahoma, Head Start schools and public elementary schools are closely linked. In Tulsa, Oklahoma, Head Start schools are run by an organization called

CAP Tulsa. They share resources with Tulsa public schools and, in many cases, are built close together. Everything the children are doing in the classroom is intentionally arranged to stimulate their development in every respect. I am the executive director of CAP Tulsa. We were observing these children using these colorful, tiny tiles that they were gluing onto the first letter of their name. That type of skill, that fine motor skill development, prepares them to hold a pencil. I visited both CAP and public elementary pre-k classrooms to see the kinds of activities she met, like identifying the parts of a book, and creative problem-solving and collaboration. It's how to get along with people, how to self-regulate. And it works. Decades of research shows that kids that experience high-quality education environments as four-year-olds show up to elementary school with an advantage. Kindergarten teachers always know the children that have come through our program because they are the children that know how to be in school.

You can really understand the impact of that when you see kids who didn't have this experience.

Take a look at this video of Oklahoma five-year-olds in the 90s.

Red. Okay, what color is this? Green. And what's this one? Red.

These kids were entering kindergarten, but some couldn't count to five. Is that five?

Seven, eight, nine, ten, eleven, fourteen...

So why doesn't every state have this? One maybe obvious barrier is funding. Not all lawmakers are convinced that the educational benefits of free pre-k for all are worth the money.

But one group that is particularly wary of free pre-k is the private child care industry, and kind of for good reason. It all comes down to the business model of private child care.

One of the biggest costs to a certified child care center is hiring qualified teachers, and each age group requires different teacher-to-child ratios to ensure adequate care for each child.

Infants need the most care, so their required ratio is the highest, and these classrooms are the smallest.

As you move up to four-year-olds, your oldest group before they head off to public kindergarten, that ratio is lower, so the same number of teachers can accommodate a much larger group of kids.

So if you think of each teacher as a cost and each kid as a client, four-year-olds are the most profitable for these private child care providers, and subsidize the pricier infant care. Take them out of the equation by enacting universal pre-k, for example, and you risk bankrupting these child care centers or passing on unmanageable costs to working parents who need this service. This argument that universal pre-k hurts child care has come up as Texas has tried to expand pre-k access, but that didn't happen in Oklahoma, in large part because of this man. My name is Joe Eddins. I'm a retired member of the

Oklahoma House of Representatives. His universal pre-k bill and a loophole in the law. In the late 1990s, I was able to add a 14th grade, and we called it pre-kindergarten. Kindergarten in the

U.S. is for five-year-olds, but in the mid-90s, some Oklahoma school districts started to notice a hole in the state's new kindergarten law that incentivized them to add four-year-olds to those classrooms. This is how the loophole worked. The bill said that school districts could offer either a half-day kindergarten program or a full-day program, and the districts received funding based on the number of kids enrolled. But the law didn't say a half-day program counted less than a full-day program funding-wise. A student enrolled in either one earned the same amount for the district. It didn't take long to figure out that you could have two half-day programs in one day and get double-funded. This was just a moneymaker. One teacher could have the full money coming in in the morning, and then another set of full money coming just like the bank truck came by twice a day. And that was an incentive for schools to have a lot of kindergarten. Which is why four-year-olds were being added to these classrooms. More students enrolled in kindergarten meant more funding. Once school superintendents understood that a lot of people were doing this, and they figured out the money involved, they jumped on it. This was a problem for the state.

I had a worksheet that showed here's what we're doing last year, this year, and what'll happen next year as other school districts jump on this deal. To keep schools from packing kindergartens with four-year-olds, Joe's bill proposed setting up early childhood programs at any public school that wanted it. It would be free of charge, just for four-year-olds, and, crucially, he struck out this part, who meet the qualifications for Head Start.

With this one piece of one sentence removed, Joe was proposing a universal program. But to catch that, you'd need to read the bill closely. And Joe didn't say, this is the bill that creates universal pre-k, even though that's exactly what it was. What he said was, this is the bill that keeps four-year-olds out of kindergarten, and it's voluntary for everybody, and I sat down. The bill also said school districts could use their funding to contract with existing early child care providers. They could get state funding to start a four-year-old program and use it to hire early childhood education programs already in place. It, of course, would have to meet the standards, and I did not explain to them that it was going to be Head Start. But since the bill didn't seem to threaten private child care's four-year-old clientele, and very few others fully understood it anyway, no one who actually understood the bill told lawmakers to vote no. If a lobbyist does not come into your office and explain this law and why you should vote no on it, the legislator doesn't have any help except me. It passed the House 99-0. Once the word got out about free, high-quality pre-k, Oklahoma parents jumped at the opportunity to enroll their four-year-olds in their local elementary school. It got to where they started lining up in the early, early hours of the morning so that they could be in their neighborhood school. Part of it was they needed child care. Andy and Jana McKenzie taught in early childhood education in Tulsa public schools for 40 years. That's Jana conducting kindergarten assessments in that video back before Oklahoma had free pre-k. These two were instrumental in setting up the existing pre-k program, including in forging the close partnership between Head Start and public schools still in place today. And I think parents very quickly realized that it was a great place for their child to be. Offering pre-k in Oklahoma school districts was and still is voluntary. But 27 years later, free high-quality education for four-year-olds is offered in public schools in every school district in Oklahoma. Because even though red states like Oklahoma don't generally support big social policies, there's nothing really controversial about it at this point.

It's established. There are results. Families are happy. Communities are happy. They know it's a good program. They see the success of the children and how much they love school.

In Oklahoma, pre-k is just when school begins. I don't run into anybody anymore that doesn't know that there's a pre-k program. It's there. It's just part of what we offer. And most of them, because they need it for child care, go ahead and sign up. Implementing universal pre-k isn't easy or cheap. You need qualified teachers and often construction of new facilities. But the biggest lesson from Oklahoma for me was if states can find a way to do this, whether it's through groups of dedicated advocates and educators demonstrating why it's good for kids and parents, or it's through a little wheeling and dealing, the programs once in place are beloved across the political spectrum. It's a wonderful program and fills the need of a lot of parents. Where do they want their children to be when they're four years old? Just this year, a Republican lawmaker in Oklahoma introduced a bill that would expand free pre-k to all three-year-olds in the state.

It hasn't passed, with some lawmakers noting the pressure it would put on private early childhood education centers. But just the fact that a Republican wanted to offer free education to all three-year-olds is just so Oklahoma.