This is likely the book you are looking for if the title is exact. It is an educational guide focused on breaking gender stereotypes from a young age.
: The book explores how cultural references and games train children to behave according to their gender—pink for girls (submissiveness) and blue for boys (strength). Educar en el feminismo.epub
: It provides tools for parents and teachers to raise "free" children rather than "brave" or "obedient" ones, advocating for "coeducation" where no activity or trait is gender-locked. This is likely the book you are looking
Often searched with this title, this "feminist manifesto" is written as a personal letter. Educar en el feminismo - WordPress.com : It provides tools for parents and teachers
: Marañón highlights a study showing that by age 6, girls already start feeling "less intelligent" than boys due to these ingrained biases.