The pattern
Forming and simplifying ratios
Keep the quantities in order and divide both by the same number.
A ratio is two or more amounts written side by side, in the order the question names them: red beads first if the question says red to blue. Because both amounts count the same kind of thing, beads, there is no converting to do, only writing the numbers down in that order. Simplifying a ratio means dividing every number in it by the largest number that divides them all evenly.
How to spot it
The question names two quantities in a stated order, red to blue, or gives an existing ratio to reduce. Words like 'ratio' and 'simplest form' give it away.
Common mistake
Children write the numbers in the order they appear in the story rather than the order the question asks for. When simplifying, they divide only one of the two numbers instead of both.
4 worked solutions
Standard
- Red and blue beads — 18 and 24 There are 18 red beads and 24 blue beads. Write the ratio of red beads to blue beads.
- Red and blue beads — 24 and 32 There are 24 red beads and 32 blue beads. Write the ratio of red beads to blue beads.
- Simplify the ratio 18 : 24 Reduce 18 : 24 to its simplest form.
- Simplify the ratio 24 : 32 Reduce 24 : 32 to its simplest form.
All the problem patterns → · the revision list
The 33 problem patterns
All 33 patterns, one to a page — the 19 behind Primary 5 and 6 word problems, and the skills the younger years are built on. The bar model, how to spot it in the question, and the mistake children make. A booklet you can print. Free.
A PDF, and a note when new solutions go up.