Since he had started school, Robert, previously so happy and lively, was becoming much quieter and more reserved. He was only four and a quarter when, in line with local education policy, he was obliged to start school. I was convinced that this was too early. Some time later I read that the psychological difference between a four-year-old and a five-year-old is the same as the difference between a seven-year-old and an eleven-year-old, and that starting school at such a young age is actually damaging to a child’s development.
— Travelling to Infinity (Jane Hawking), Loc. 2829–33