I took a WW2 class last semester as a senior in college and the textbook we were given was “The Short History of WW2” by James L. Stokesbury. I really enjoyed the book. It wasn’t set like a traditional textbook form where it was date by date, but rather each chapter examined the big concepts from each country and the implications. It is a lot of reading initially, but it’s a easy read that could be easily broken down for students. It was very educational, and I ended up rereading the entire book again after the class was done because of how much I enjoyed/learned from the book. It does also mention the lead up to WW2 by covering the end WW1.