I plan to use Game Maker as the programming language.

This is because one of my goals is to model a process that I have asked my year 11 students to do: to design and make an educational game using Game Maker

Some advantages of Game Maker:
  • many inbuilt specialised easy to use game making features such as collision events, alarm (clock) events, etc.
  • great drag and drop interface, which makes it easy to get started
  • low entry, high ceiling - for more advanced programming a code window and hundreds of functions are available
  • the source code is readily accessable to students because of its low entry
  • a very good free version is available from http://gamemaker.nl/
  • large, energetic community

Some disadvantages:
  • not open source, that is the "complier/interpreter" is not but the game will be
  • not web compatible
  • only available on the Windows platform
  • requires DirectX even to run its *.exe files
  • limited 3D support
  • the full featured registered version is less accessable at home

If others want to diversify and make a version of the game we design here in a language without the disadvantages listed, such as squeak or python, then I'd be delighted

BOOKS:
The Game Maker's Apprentice by Jacob Habgood and Mark Overmars
The Game Maker's Apprentice shows you how to create nine exciting games using the wildly popular Game Maker game creation tool. This book covers a range of genres, including action, adventure, and puzzle games--complete with professional quality sound effects and visuals. It discusses game design theory and features practical examples of how this can be applied to making games that are more fun to play.

Squeak: Learn Programming with Robots by Stephane Ducasse
(the robots refer to on screen robots and turtles)
... introducing young students to squeak and programming concepts. The reviews are good

Python Programming for the absolute beginner by Michael Dawson
Introduction to Python through building games like word jumble, hangman, tic tac toe etc.

Game Programming with Python by Sean Riley
More advanced than previous book