The Pacific Research Institute noted, "In January 2006, UC-Santa Barbara researchers found that whatever student achievement gains can be attributed to preschool attendance largely evaporates after a few years in elementary school. In other words, by about 2nd grade skill levels of children who attended preschool and those who did not were the same and remained so throughout the rest of their education."There is a practical cost as well. Another year of education costs a great deal of money at the back end.
If we assume that today it costs roughly $8,000 per pupil for a year of education (a figure that falls somewhere in teh middle of the per pupil expenditure range) and furhter assume annual inflationary increase of 3% per year, at the end of a regular K-12 eduction, the annual cost to educate one kid is $11,406 and a total cost of 12 years of education of $124,942. If you add one more year, the final year cost is $11,748, which a three percent difference, but the total cost of a 14 year educational process is $136,690, a nine percent increase.
These figures don't assume any other changes like the larger than inflationary increases in school budgets that are normal, usually between five and ten percent increases.
In the long term it may be proven that pre-K is valuable, in which case we can evaluate the funding issues, but if the improvements afforded by pre-K disappear by teh time the child is in the thrid grade, I fail to see the long-term benefit of universal pre-K.