There is another issue she does not mention: it can be be difficult, if not impossible, to successfully bring to scale those small interventions that work under carefully controlled contexts.
The problem is that there’s no evidence that universal pre-K comes even close to its touted capacity to move the needle for disadvantaged children. Pre-K advocates widely cite two well-run demonstration projects from a half century ago – Perry Preschool and the Abecedarian Project – as proof that pre-K has lasting benefits for low-income kids. Perry Preschool, run from 1962 to 1967 in Ypsilanti, Michigan, placed a total of 64 three- and four-year-old poor children in morning preschool for two-and-a-half hours per day and made weekly home visits to their mothers. Abecedarian, run from 1972 to 1975 in Chapel Hill, North Carolina, placed a total of 57 poor children in a full-time, full-year, high-quality childcare/preschool setting from infancy through age five. Both programs had major positive impacts on participants’ educational and life outcomes, sustained for decades into adulthood, with big economic benefits to society through lower social welfare costs, decreased crime rates and increased tax revenue over the lifetimes of program participants.
Skeptics point out that Perry and Abecedarian were small, boutique programs, carried out decades ago, with limited applicability to large-scale pre-K in 2015. But perhaps the most important problem is that the design of those programs bears little resemblance to pre-K – much less universal pre-K – in the first place. Perry could just as well have been called the Perry Home Visiting Project, since the weekly home visiting component of the program was at least as intensive as the 15-hours-per-week preschool part. And Abecedarian wasn’t even a pre-K: Children were enrolled full-time starting when they were infants, not at the preschool age of three or four.