Here’s an NPR  piece you can listen to or read that captures the central tension of President Obama’s universal pre-K proposal:

WERTHEIMER: Now, President Obama says that spending money in preschool gives us a return that is seven times the investment. Where does that number come from?

VEDANTAM: Those numbers come from a couple of studies and called the Perry Preschool program and the Abecedarian program, Linda, that targeted very high quality and fairly expensive interventions at very disadvantaged children. And what those programs found – they followed these children out, not just for years, but for decades – is that the programs didn’t have just cognitive benefits – in other words, improvements in performance in academic scores – but they had life benefits. They had reduced the teen pregnancy rate. They reduce the crime rate. They had huge benefits later on.

So the president is on very solid footing when he talks about the return investment when it comes to those narrowly targeted programs.

But what he rhetorically links those programs with larger programs, such as the experience in states, such as Oklahoma and in Georgia, in some ways he’s venturing off the ledge of science. There have been studies looking at the experience of those states. And I have not seen any data that suggests the return on investment in those states is anywhere close to seven times our investment.

…..

more here: Is The Call For Universal Pre-Kindergarten Warranted? : NPR.