Defining tone is so challenging! - This reference uses words which appear on the ACT and SAT - to give students a guide when looking for an author's attitude. Words are in alphabetical order and numbered (students are intimidated when they see a word they know applies but can't pronounce - this helps them order a tone word by number in class discussion, allowing the teacher to pronounce it and further discussion with the student). I've had such success with this - all students have the ability to participate. Enjoy discussing tone in your classes!