Four pictures One word game

I have made this for a lesson where I want to revise key terms. The game is very popular on the iPhone at the moment and would be a great way to introduce or revise key terms. There is a very easy example of slide two how it looks. But the aim of the game is to look at the four pictures, use the letters at the side to find the key term/word. Some times it could be more obvious like the example or perhaps it could be how the images link.