Unit 19 · Unitary Method
Unitary Method
Mathematics · Grade 7
What You Will Be Able To Do
1️⃣Solve a proportion problem in two clear steps, through one unit
↕️Know whether the first step is a divide or a multiply, and say why
🔀Handle problems where two things change at the same time
🛒Work out which pack size in a shop is genuinely the best value
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The unitary method is two steps and nothing more. Work out the value for a single unit, then multiply up to however many units the question actually asks about.
Presenter notes: Open by reminding the class of something they already did. Two units ago, when checking whether seven pens cost 105 rupees, somebody worked out the cost of one pen first and then multiplied. That side route has a name and it turns out to be the safest method in the whole of proportion work. Today it gets used deliberately rather than as a check.