Preface to the Classic Edition Preface to the 2014 edition 1. The Class Inclusion Problem in Piaget's Theory 2. Teaching the Inclusion Problem to Children in Geneva 3. Teaching the Inclusion Problem to Children in Amsterdam 4. A Genevan Comment on My 1963 Publication 5. Teaching the Inclusion Problem to Children in Montreal 6. Teaching the Inclusion Problem to Children in Utrecht (Netherlands) 7. Categorizing Children According to Their Degree of Understanding 8. On the Methodology of Learning Studies Relevant to Piaget's Theory Summary Epilogue A Personal History Bibliography Author Index.