Ratio
Ratio is multiplicative comparison. Bars make before–after and constant-difference problems thinkable. Students write a:b and a:b:c in lowest terms, distinguish part-to-part from part-to-whole, and solve before–after problems with a changing quantity, a constant total, or a constant difference.
Specification · for a parent or teacher
- ratio-tape-diagrams
- Advanced Math 5 · Unit 13
- Applied
- 3 of 4 — Grade 6–7 core. Multi-step, first symbolic work.
- 3 items
Students can
and in lowest terms; part-to-part and part-to-whole; before–after with a changing quantity; constant total; constant difference.
Ready when
“Ali and Bea have beads in the ratio 3:5. Ali gives Bea 4 beads and the ratio becomes 1:3.” They can find the start.
Watch for
treated as of the whole rather than 2 of 5 parts; before–after drawn as one bar.