I have the Simon and Schuster "Pocket Book of Chess". It's a bit wordy, but it covers all the rules, a bit of history, and also has some openings and bios of some of the more famous players along with examples of their games. I believe I got it when I was in 3rd grade or so, and i had no trouble reading it.
Need book with fork/pin/skewer/etc diagrams

I would recommend Ward Farnsworth's Predator at the Chessboard. It is broken down into tactics, discoveries, pins, skewers, removal of the guard, and basic checkmates. Each section has many examples all with diagrams and also a written explanation of what you should be thinking and looking for in each problem. He starts with very basic problems and moves towards more complex. Should be perfect!
One book that covers all the basics is "Winning Chess" by Chernev & Reinfeld. I believe only available in used copies from Amazon.com.
Appreciate the input. I looked at a couple. Am looking for something that is more heavy on the actual diagrams of forks/pins/skewers, etc. rather than something that explains each of these. I want to have a lot of diagrams to use in chess club, as homework, etc.

Appreciate the input. I looked at a couple. Am looking for something that is more heavy on the actual diagrams of forks/pins/skewers, etc. rather than something that explains each of these. I want to have a lot of diagrams to use in chess club, as homework, etc.
"1001 Winning Chess Sacrifices and Combinations" by Fred Reinfeld
http://www.amazon.com/Thousand-Winning-Chess-Sacrifices-Combinations/dp/0879801115

4th grade to 6th grade? Do you mean D class to F class? or 1400 to 1600?
I took it to mean 4th and 6th graders as in children in elementary school- i believe you call it primary school on the other side of the pond?

You could do worse than try Paul Littlewood's book 'Chess tactics' published by Batsford. This is quite good in terms of brief descriptions of different topics with some illustrations and then a series of tests. It is more rich in diagrams than text.
I have just checked and it includes 307 diagrams, implying (I think I am right in saying) 307 different examples or tests. The first 14 chapters have ten tests each and there is a final chapter with 20 tests of different types. So, 160 tests and the remaining diagrams providing examples. I find it the best succinct and summary book on tactics I have seen so far.

Hello,
the best way to learn tactical patterns with pins/forks/skewers is to do a lot of tactical exercises.
For the fork, I have written a blog post just here: http://chesstrainerapp.blogspot.fr/2014/01/the-fork.html

Best one I ever found: Chess Traps, Pitfalls and Swindles by I.A.Horowitz (Fireside Chess Library). Hope this helps!
I have begun teaching a 4th-6th grade chess club and I am looking for a book or computer program with as many diagrams of pins/skewers/forks/discovered check, etc. as possible, preferably at a beginning/intermediate level. What is a good resource?