A Tarsia activity on the important aspects of ratio. 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 spot any (non deliberate!) mistakes, please share them below. Many thanks to all the teachers who have helped me assemble these Tarsias over the years.