Mathematics Ratio & Proportion Representational 9–12 yrs

Bar Models for Ratios

比率条形模型

Description

Represent ratio and proportion problems using bar models (rectangular strips divided into equal parts labelled with quantities) and tape diagrams (segmented strips showing part-to-part and part-to-whole relationships); use these visual models to set up and solve unequal sharing, scaling, and percentage problems — drawing the diagram first, then reading off the answer

Mastery Evidence

✓ Draw a bar model to represent a ratio problem — e.g. sharing £20 in the ratio 3:2 by drawing 5 equal blocks
✓ Use a bar model to solve a proportion problem and explain each step
✓ Compare bar models with other representations (tables, double number lines) and explain when each is most useful

Assessment Prompt

If your child needs to share 30 stickers between two friends in a 2:3 ratio, can they draw a bar model — splitting a strip into 5 equal boxes — and use it to work out each share without just guessing?