VALUE OF UNIVERSAL PRE-K “not empirically validated.”

As California discovered when it tried, and failed, to replicate class-size reduction results from the relatively small Tennessee STAR program, scaling presents big challenges such as getting enough good teachers to staff all the new positions.

Or consider Head Start and Early Head Start, federal early childhood programs that have undergone random-assignment scrutiny. They have demonstrated very few lasting benefits, and some negative effects.

To be fair, Salins argues that Head Start “was never designed to be a true preschool program,” but is instead “a well-meaning daycare program.”

Well, it depends on what you mean by value. If your goal is to produce more unionized public employees. . .