Unit 17 · Ratio and Proportion
Ratio and Proportion
Mathematics · Grade 7
What You Will Be Able To Do
⚖️Write and simplify a ratio, with the units matched first
🍰Share any amount in a given ratio, and check your answer
📈Solve for a missing quantity when two ratios are equal
🔁Tell direct from inverse proportion before you start calculating
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A ratio compares two quantities directly against each other, with no whole in sight. That is exactly why it survives being scaled up or down.
Presenter notes: Open with a mixing question. Ask how a mason knows how much cement to use when the size of the job changes every day. The answer is that they do not remember amounts, they remember a ratio: two parts cement to three parts sand, which works for a bucket or a lorryload. Last lesson compared a part with a whole; today compares two parts with each other, and that small change is what makes recipes, maps and mixtures work.