MEI have an excellent free collection of GCSE starters. Designed for the start of a GCSE lesson, the diagrams and questions are very clear and will display well on the IWB. There are several starters under the following headings: Mathematical Reasoning, Number, Algebra, Geometry and Measures and Statistics and Probability. Files with the answers and teachers notes are also provided.
It is not always possible to have the IWB up and running, particularly if you are coming from a different room and I do like to get students working straight away. Experimenting, I found that I could tale a screenshot (I do like the snipping tool in Windows 7) and fit eight to a page! I used a Word document with very small top and bottom margins and a two column layout.
For more ideas on a calm start to lessons – getting everybody working straight away – see Bell Work.