The book "What Every Mother Should Know; or, How Six Little Children Learned the Truth" was written by Margaret Sanger, a well-known American leader of the women's rights movement and popularizer of family planning. In this book, she shares her experience of raising children and improving teaching methods. Sanger tells the story of six young children who, through their own research and openness to new ideas, gain knowledge and understanding of the world around them. This book is a combination of a pedagogical textbook and an intellectual game aimed at developing children's thinking and critical thinking. "What every mother should know" is not just a book about upbringing, it is a book about how to teach children to appreciate the truth, develop their mind and emotional intelligence.