I'd like to share with you in a quick post the summer 'homework' I suggested for my students this year. Besides the classic graded readers to practice reading comprehension, I thought that some puzzle/quizz/riddle book might be, not only entertaining, but also a good way for connecting the different areas of knowledge (English, Natural and Social Sciences, Maths, etc.) in order to enhance significative learning and the 4 language skills (reading, writing, listening, speaking).
So... here's some of the books I selected for primary school students starting from National Geographic, which has some good ones:
Then, I thought about brain teasers, which are useful for learning how to think outside the box. They usually come with the age of the children they are designed for. However, since they are for native speakers, I would pick a level below your child's age if yours is not. Also I would choose the paperback version which usually comes with pictures and illustrations.