Free preschool for needy kids. They are the kids who are unprepared for preschool and fall further and further behind their peers as they progress through school. We need to invest in them as an investment in our future. And this investment will pay off the costs by orders of magnitude.

https://eric.ed.gov/?id=ed366433

"Study findings at age 27 as reported in these chapters indicate that the preschool participants have significantly higher earnings, rates of home ownership, and levels of schooling, as well as significantly fewer arrests and social service interventions, than a control group of non-preschool participants. Cost-benefit analysis revealed that, over the lifetimes of the participants, the preschool program returned to the public an estimated $7.16 for every dollar spent."