Reading Math “General Audience” books can be a really enlightening experience. Not as dense as Math textbooks, they tell the story behind the great discoveries of Mathematicians. It is an excellent choice for parents who want to inspire and motivate their child about the beauty of Math, which is not just about exams / doing endless exercises.
Recently two books on the Poincare conjecture on Amazon caught my eye. This is the famous conjecture solved recently by Grigori Perelman, who is the first person ever to reject the Fields Medal. Definitely looking forward to read these two books.