Unit 7 · Perimeter and Area
Perimeter and Area
Mathematics · Grade 7
What You Will Be Able To Do
🚧Tell instantly whether a question wants perimeter or area
📐Derive every area formula from the rectangle, instead of memorising five
🏠Handle an L-shaped room by splitting it or by subtracting
💰Work out which of two plots with the same boundary is worth buying
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If a field is your shape, the perimeter is how much fencing you need and the area is how much grass there is. They answer completely different questions.
Presenter notes: Open with a question that has money in it, because that is what makes this unit feel real. Say a family is buying land and two plots cost the same and both need the same length of boundary wall, but one gives three times as much usable ground. Ask how that can be, and let them argue for a minute without settling it. Tell them that by the end of the lesson they will be able to work out which plot to buy, and that people genuinely lose money by getting this wrong.