From my bookshelf comes a very easy to read book about the history of Mathematics. Mathematicians are People, Too is a delightful book written by Luetta and Wilbert Reimer (1990).
The stories are interesting, well written, and have great illustrations. The reading level would be appropriate for many secondary school students and some upper primary school kids as well.
I particularly like the first story about Thales, titled “Pyramids, Olives, and Donkeys”.
I highly recommend this book to teachers to help give their students a greater interest in, and hopefully a love of Mathematics.