How valuable is kindergarden?

According to new studies, kindergarten is very valuable - at present value, an outstanding kindergarten teacher is worth $320,000. Wow. David Leonhardt sums up this research showing the value of good teachers in a dollar amount. Interestingly, the real added value does not show up on test scores - which implies that there is something besides knowledge that teachers give their students that is of real value. Of course, that is what teachers have been saying for a long time. Now the numbers show it.