R.M. Beard 
An Outline of Piaget»s Developmental Psychology [PDF ebook] 

First published in 2006. This is a book for students and teachers who wish to know more about Piaget»s work but who find it too difficult, or time-consuming, to read much in the original. Its purpose is two-fold: both to make some of his ideas and observations available fairly quickly to the reader, and to introduce most of his special vocabulary, so facilitating reading in the original.