Describe a ratio relationship between two quantities in words, with a colon, and as a fraction, distinguishing part-to-part from part-to-whole.
RATIO.RATIO_LANGUAGE“I can write a ratio correctly and say whether it compares part to part or part to whole.”
For 8 red and 12 blue counters, give the part-to-part and part-to-whole ratios and explain the difference.
| Course | Unit | Depth | Role | Checkpoint |
|---|---|---|---|---|
| Grade 6 | Ratio and rate | intro | introduce | ✓ |
Equal-sized blocks allocated to each part of a ratio so a:b is visibly a+b units.
Ratio sharing without setting up a proportion.
engine: segmented bar with per-part colouring
Rectangular bars segmented to show parts inside a whole, with the unknown drawn as a labelled gap.
Word problems become a picture you can read the equation off.
engine: segmented bar actor with labelled brace
A table of equivalent ratios scaled up and down by multiplication, not addition.
Scaling arrows make the multiplicative structure explicit.
engine: table widget with scale-factor arrows
Scene archetype: bar_model
RATIO.LANG.PART_WHOLE_MIXWrites 8:12 when 8:20 is meant.
Repair: Label the whole explicitly before writing the ratio.
One row per instructional system. Rows marked cluster carry authored treatment for this family of topics; rows marked template are derived from the system’s general pattern and are not topic-specific research. Confidence is recorded on every row.
Ratio and rate get a dedicated Grade 6-7 domain as the explicit bridge into algebra, with the double number line and the ratio table introduced as reasoning tools so that proportional relationships are met before cross-multiplication.
Ratio is taught as units: a 3:5 ratio is eight equal blocks, and almost every ratio problem is solved by finding the value of one block from a drawn strip. Formal proportion machinery is rarely needed.
Ratio and proportion sit inside a large body of multi-step problems about parts, rates, and scaling, worked through condition tables. Solving a proportion is the easy part; setting one up from a tangled situation is the taught skill.
Ratio appears as fraction-style computation and proportion solving within the fraction and pre-algebra levels, drilled as cross-multiplication rather than as multiplicative reasoning.
Proportional reasoning is developed through per-unit quantity, with the double number line used to keep the two measures aligned. Lessons compare a student who scaled up with one who found the unit rate.
Ratio and proportion are presented as a set-up-and-cross-multiply procedure with extensive practice, appearing in the pre-algebra book and then recurring in mixed review.
Ratio work grows out of the elementary material on multiples and proportion in geometry, particularly with the constructive triangles and similar-figure work, and is more geometric than numeric.
Ratio is treated as a route into scaling arguments and later into similar-triangle and probability reasoning, with problems where the naive proportion set-up gives the wrong answer.
Ratio and proportion are a named KS2-KS3 strand taught with bar models and ratio tables, with careful separation of part-to-part from part-to-whole and a lot of "for every" language.
The Grade 6 ratio units are among the most carefully built in the curriculum: discrete diagrams, then double number lines, then tables, with each representation introduced when the previous one becomes inconvenient.