I am a very big fan of The Number Devil written by a famous German author (normally known for his books about history or politics). The subtitle in the original German version is "Ein Kopfkissenbuch für alle, die Angst vor der Mathematik haben." (=A pillow book for all fearing mathematic.")
It's a (nicele illustrated) story about a boy having fear of mathematics in general and fear of his math teacher. He dreams every night of the so-called number devil who will teach the boy the beauty of math.
The very special thing about the book is the fact that mathematical terms are not called how we would call it, but with special colorful words (e.g., the number devil explains the boy why multiplication is important and how it is derived from addition. Then, the number devil does an analogy of it to introduce factorial - But the book calls it "Wumm!". So the boy is teached to perform e.g. "6 Wumm!". Taking roots are called taking rutabaga, etc.). One can discuss if this is good or bad, but at least this doesn't sound like mathematics known to students in that age and is maybe motivating students to have interest in mathematics. (There is also a table at the end of the book translating the new terms to known terms for us. This table can also be helpful to students who might say: "Okay, I understood the concepts of the book...Wait... This rutabaga thing was the complicated root thing our teacher explained a few weeks ago?")
More or less, every night (I think, there are about 10?) is one "lecture". The mathematical content is about mathematics teached to students in the age of 10-14 maybe (depends on countries, etc.), but also has some hints to college related questions: Firstly, the book introduces basic operations like factorial, roots, etc and also numbers systems like natural numbers, rational numbers, etc. (and even a small adventure to complex numbers). Then the book deals a lot with pascal's triangle, Fibonacci numbers and related content. At the end, there is small journey into more advances subjects like topology, the traveling salesman problem, etc.
I hightly recommend the reading of the books - even (or in particular!) for adults.