Level 4: Percent

Ratio, rates and money · level 4 of 8 · rough age 11-12 (a guide for parents; anyone can start anywhere)

A percent is a ratio with the second number fixed at 100, and that one small idea makes comparing almost anything easy. In this level you see percents on a hundred grid and move between fractions, decimals and percents; find a percent of any amount in your head; turn test scores and survey results into percents; and then use it all with real money: sales tax at the till, discounts in a sale, and a monthly budget that balances.

Lesson	You will be able to
Percent means per hundred	Show a percent on a hundred grid and write the same amount as a fraction, a decimal and a percent
Percent of an amount	Find any percent of an amount by building from 10%, 5% and 1%, or with a decimal, and explain why \(a\%\) of \(b\) equals \(b\%\) of \(a\)
One amount as a percent of another	Write "this out of that" as a percent and compare results with different totals
Sales tax	Add 13% HST (or 5% GST) to a price or a bill, round for cash, and find a price before tax
Discounts and sale prices	Find a sale price in one step, compare a percent off with an amount off, and see through "buy one, get one" deals
Budgets	Build a monthly budget with fixed and variable costs, show its parts as percents, and fix one that does not balance

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