Putting the Sex Ed classes into a broad category of 'improving people's mental health' may give quantifiable estimates of benefit[1]. The monetary benefits of regular education (most directly measurable at the university level [2]) are an order of magnitude less valuable (on a happiness-per-dollar basis).

Normally, I'm not really a fan of the 'soft' subjects (compared to the hard sciences). But giving people at least a minimum level of knowledge about something as basic to life as sex (or understanding depression, for instance) should (IMHO) be a priority.

[1] http://en.wikipedia.org/wiki/Happiness_economics#cite_ref-13 [2] http://blogs.reuters.com/reuters-money/2011/06/06/is-college...