Level 3: Ratios and rates

Ratio, rates and money · level 3 of 8 · rough age 9-10 (a guide for parents; anyone can start anywhere)

In level 2 you said "for every" and filled in ratio tables. In this level that idea gets its own notation, \(3 : 2\), and its own rules: why multiplying both parts keeps a mix the same while adding does not, how to share any amount fairly in a ratio with a bar model, and how to compare things of different kinds with a rate. You will find the best buy in a shop, work out speeds and travel times (even to Mars), and finish by planning a real party budget.

Lesson	You will be able to
Writing a ratio	Write a ratio in the right order, tell part to part from part to whole, and turn a ratio into a fraction of the whole
Equivalent ratios	Make equivalent ratios, simplify a ratio, and decide which of two mixes is stronger
Sharing in a ratio	Share an amount in a ratio with a bar model, even when you know only one share or the difference
Rates and unit rates	Find a unit rate, use the unitary method, and find the best buy
Speed as a rate	Find any one of speed, distance and time from the other two, change km/h to m/s, and find an average speed
Planning a budget for an event	Plan a party within a fixed amount, estimate safely, and fix a plan that goes over

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