Students learn how to model variations of direct and indirect proportions by setting up an equation. They learn how to solve this equation to find k, the constant of proportionality. As learning progresses students illustrate these linear and non-linear using graphs.
My experience as a Head of Mathematics going through the deep dive OFSTED inspection.
How to use ratios and proportional reasoning as a model for finding the original amount after a percentage change.
To find the area of compound shapes students need to understand what the word compound means.