Proportion · Grade 5
In Grade 5 you learn: scaling recipes.
Two quantities are in direct proportion when they grow together at the same rate: twice as many tickets cost twice as much. In inverse proportion one goes up as the other goes down: twice as many workers take half the time. The unitary method — find the value of one — solves almost every proportion problem.
Key facts
- Direct proportion: both quantities are multiplied by the same number.
- Exchange rates: multiply to change into the new currency; divide to change back.