Fun fact: the monikers used for these children in the book are used in coloquial speech to describe children that misbehave or exhibit behavioral discrepencies:

• shock headed Peter: an unkempt, filthy child
• fidgety Philip: ADHS or hyperactive child
• Johnny-Head-in-the-Air: daydreaming, absent mindedness
• wicked Frederick: cruelty to animals (sociopathy, lack of empathy often reveal themselves this way early on)
• Soup Caspar: eating disorder, perhaps
• etc

The original book was written by a medical doctor dealing with children, go figure!