Grade 5 › G5U07 Ratios

Grade 5 › G5U07 Ratios › L1
GRADE 5 · ALBERTAOUTCOME AB-G5-5N7

L1 · What a ratio is: part-to-part and part-to-whole

Learning goal

“I can write a ratio to compare two quantities - part-to-part (one group to another group) and part-to-whole (one group to all of the groups put together) - and I know the order of the numbers matters.”

Ratio — a comparison of two quantities in a specific situation, written with a colon, like 3 : 5, and read "3 to 5."
Part-to-part ratio — compares one part of a situation to another part (apples to oranges: 3 : 5).
Part-to-whole ratio — compares one part to the whole amount (apples to all the fruit: 3 : 8).
"For every" — the words we use to say a ratio out loud: "For every 3 apples, there are 5 oranges."
Worked example

A fruit bowl has 3 apples and 5 oranges. Step 1: Name the two quantities in the order the question uses: apples first, oranges second. Step 2: Count each part: apples = 3, oranges = 5. Step 3: Write the ratio in that order: apples to oranges = 3 : 5, read "3 to 5," or "for every 3 apples, there are 5 oranges." Bar model, in words: one bar, split into 8 equal parts - the first 3 parts are labelled "apples," the next 5 parts are labelled "oranges." Ratio table, in words: a row for apples says 3; a row for oranges says 5. Say it plainly: the FIRST number always matches the FIRST thing named.

Check yourself — explain it

Why does 5 : 3 NOT describe apples to oranges in this bowl?

Paired problem — example still visible

A drawer has 4 red pens and 6 blue pens. Write the ratio of red pens to blue pens -> 4 : 6

Faded completion — last step is yours

"There are 7 boys and 4 girls in a club. The ratio of boys to girls is ___ : ___" -> 7 : 4

Ready to practise?

10 scored questions with a 3-rung hint ladder. Mastery needs 8/10 plus both gate questions.

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