This lesson includes a starter, compromising of retrieval questions. It then goes onto look at writing ratios, with some examples and a think,pair, share activity. It then explores simplifying, including a recap of HCF, a simplifying ratios RAG activity, and some word problems as an extension. This includes a notebook and a powerpoint version. Answers included. I used this for a low ability year 10 class, but this could also be used for any KS3 or primary class.