A brilliant Tarsia activity by Gill Hillitt on factorising quadratics. These type of activities can be used to consolidate understanding of a given topic, and foster positive group work and co-operative learning. For more ideas on how to use these types of activities (including twists!) and to download the latest version of the wonderful free software to open this resource (and create your own), just click on the web-link. If you have any comments or feedback for Gill, please share them below.