Rates is a theme within ratio and proportional reasoning. Links to relevant activities and resources are on the right hand side of this page.
One way to deal with proportional mixtures is to develop a language of ‘so-much-per-so-much’. This language is a useful link to composite measures such as density (so much mass per unit volume) or gradient (so much height per unit length). Speed is often the first rate that appears in the school curriculum, and is very hard to imagine, but early experiences of price-per-so-much and other unit ratios are also rates and can be used as bridging ideas.