Two recommendations that have been fairly prolific in scholastic circles:
- Bain's Chess Tactics for Students (tactics)
- Jeff Coakley's Winning Chess Strategy for Kids (strategy (covers all 3 phases) )
Books for Students
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Per my editted post in a different thread:
I wanted to recommend this book for people who choose self-study:
Studying Chess Made Easy by Andrew Soltis
Consider it as the most up-to-date manual or guidebook to learn how to become stronger in chess and is backed by the experience of a reputable chess writer.
If you read the few Amazon reviews, you will notice the general feeling of "I wish that I had something like this when I was starting out with chess years ago."
There will always be lists and forum threads on what books and materials to read, study and master, but this is one of those books that explains to you HOW to study any of the materials. Of course, one can argue that everyone has a different way of learning, but this book is just a guide and NOT a law.
For me, this is not spoonfeeding; rather, this is being EFFICIENT for a self-taught casual player. 
Bobby fischer teaches chess ... great all around book.
This may need to go to the chess books and equipment forum, but I thought I'd get better advice here as it pertains to scholastic chess. I'm starting a chess club at the middle school I work at and I've approached the school librarian about purchasing some chess books for our students to have access too. She said she would be happy to so I need recommendations for 5 - 6 books for the middle school aged (6 - 8th grade) chess player from beginner to intermediate. I would like one that teaches the basics of how to play chess for students who may be interested but don't know how to play yet. Then I would like one dealing with tactics and strategy. Finally I thought that having one for each phase of the game (opening, middlegame, endgame). I appreciate any suggestions up front.