School choice at sea

"Peer effects" are a potentially big issue in schools, although hard to model. How children affect each others' education can be hard to understand and measure. (What kinds of children do you want your children to go to school with, and what difference does it make?)

For bluefish, in contrast, there is a clear case for assortative matching: "Bluefish are cannibalistic. For this reason, bluefish tend to swim in schools of similarly-sized specimens."

(a market designer joke:)