What are the secrets hidden behind the behaviors not understood by parents? Opening the book, you can walk into the inner world of children and understand all sorts of seemingly inexplicable behavior motivations and be familiar with one problem you have never realized or ignored - sensitive period. After you read the book page by page, you can use the golden key in the book to crack the secrets of children in the sensitive period and accompany them to spend the sensitive period successfully. In this way, your child can grow up to be confident, caring and outstanding and have a sense of security and creativity.