See also Risps for Further Mathematics.
From Jonny Griffiths try RISPS (Rich Starting Points), Open-ended investigative activities for the A Level Pure Mathematics classroom. On the home page note the helpful index by topic, choose a personal favourite of mine, Risp 21 Advanced Arithmagons for example and you will see not only the task but also teachers’ notes.
From Jonny Griffiths – Digitisers.

What a great puzzle! Jonny Griffiths is aiming these puzzles (which always have a unique solution) at late GCSE/early A level Maths students. As Jonny says, this type of puzzle seems to engage students fast, making a great starter that revises important theory quickly; the aim of a Digitiser puzzle is to both practice and teach (or reteach) a piece of mathematics,
The image shows a simple sample task, you can find the solution on his website. The Digitisers pdf file is free. Clear instructions explaining the puzzles and notation used are given, we then have all the tasks by topic to help you pick your task – brilliant! Each task has a difficulty rating from 1 to 3 stars. Full solutions are provided.
This is a wonderful resource – puzzles like this go down well with students, but to have them all clearly by topic is perfect – thank you Jonny, for yet another amazing resource!

Choose Completing the Square for example and we have:

Also from Jonny Griffiths his companion sites on Statistics and Carom-Maths -activities to bridge the gap between A Level and University. You can find a resource collection from Jonny Griffiths on TES Resources.
Making Statistics Vital has some tasks which could be excellent for the current A Level specification, look at the this task on World Wide Statistics for example which includes the task with answers and a spreadsheet with data for 191 countries.
