Fundamental Constructs in Mathematics Education John Mason and Sue Johnston-Wilder (editors).
After an introduction to the beingness of the thinghood of constructs (named, described phenomena as far as I can tell), this book launches straight into extracts describing some of the most important and influential experiments in mathematics education. I’ve read the first chapter which describes a number of experiments that have been used to investigate the way children learn mathematical concepts. So far it has been a good deal more readable than I was expecting.