AUSTIN -- As the school year begins, many districts will benefit from an expansion of high quality pre-Kindergarten championed by Gov. Greg Abbott last session.

When Gov. Abbott signed House Bill 4 in 2015, it was the fulfillment of a campaign promise -- and a validation of what experts and advocates have been saying for years.

"High quality pre-K is a wise investment," Stephanie Rubin, CEO of Texans Care for Children, told KVUE Tuesday. "It's clear from longitudinal national research and from evaluations of state programs of those just like ours that a high quality pre-K program can improve school readiness, improve academic outcomes, graduation rates, and also reduce things like grade retention and special education, which are expensive for districts and the state."

On Tuesday, the state Senate Education Committee asked for an update on the $118 million program. According to the Texas Education Agency, which administers the grants, 603 school districts and charters applied. Of those, 599 were eligible and 578 were awarded funds. Four were determined ineligible because they are not approved to provide pre-K, and 21 declined funds.

Half of the grant recipients were notified in June, with the remaining to be notified this month. More information can be found in an executive summary and FAQ compiled by the TEA for the committee.

Part of the bill is measuring high quality pre-K's success.

"We are focused on looking at teacher observations of students to really look at how are they embracing numeracy and foundations of literacy," explained Dr. Penny Schwinn, the TEA's deputy commissioner of academics. "Those are the types of data points that we'll be collecting, and it's really about seeing what works in high quality pre-K classrooms."

The money will serve roughly 159,000 eligible four-year olds at $734 a student. That's about half what districts had initially hoped. That's what has advocates looking anxiously to the next legislative session.

"Primarily this was a step towards more funding," said Monty Exter with the Association of Texas Professional Educators. "The issue, unfortunately, is that while the formula they put in place was a good step, they didn't really put as much money into it as they could have. So it perhaps didn't fund at a high enough rate in order to allow districts to do all of the things that they wanted them to do in the bill."

"HB 4 is a good step, but we're still missing some key elements," said Rubin, "Like we don't have small enough classes and teacher to child ratios in our Texas system, and we also need more full-day options, as the research shows full-day high quality pre-K brings the best returns."