During last term I started to collect a variety of puzzles and problems taken from a variety of places and I have created a "Mr Clark's Box of Puzzles".
There are puzzles taken from a selection of books I have, some classic famous historical aspects of mathematics, some SuDoKu and similar puzzles, and a few puzzles taken from 7puzzleblog.com. When I see a new puzzle or problem, I copy/print it, and laminate it before adding it to the box.
Having the problems laminated not only makes them last a lot longer, but means that students can use whiteboard pens to write on the problems to help them solve them.
The first few times I used the box, I was introducing it to the groups, and I set aside a period of time to actually look at puzzles. We spent 20 minutes or so working on different problems in small groups or individually.
Now, however, the box has evolved into a perfect extension activity for every lesson. Students have puzzles that they have started, and when they finish their work, they can go to the box to pick it up to continue, or to find a new puzzle to start.
The students love it, and many work so much harder so that they can get on to the puzzles. The amount of thinking that goes on with each puzzle is also amazing. I am trying to get them to be as independent as possible with the puzzles (though not all of them have realised this yet). I want them to be able to approach problems and think about them before rushing to me to ask for help. I also don't have the answers for most of them to hand (though they do exist somewhere), which I find works well, as if they do ask for help, I can say that I don't KNOW the answer, but can give them ideas for how to think about it.
It is growing into quite a large collection of puzzles quite quickly, and is something that I use in all my classes, and will be able to use with many more classes. The range of puzzles means there is something there for Year 7 all the way through to A-Level mathematicians.
I am a maths teacher looking to share good ideas for use in the classroom, with a current interest in integrating educational research into my practice.