Ratio and Its Uses Review

A relationship between two quantities is written in a form such as 3:2, and children learn to find the value of the ratio and to simplify the ratio. Calculations and word problems that turn decimal and fraction ratios into whole-number ratios sit in the middle, and the work moves on to equivalent ratios and to sharing a whole in a given ratio.

When simplifying, children subtract the same number from both sides, turning 6:4 into 4:2 where division was called for. In sharing, the whole gets divided by just one number of the ratio rather than by the sum, so the two shares no longer add back up to the whole.

Finding the value of a ratio, the skill fixed in this unit, supports a property studied in the next unit, Enlargement and Reduction: that corresponding sides keep an equal ratio. The back-and-forth between fractions and decimals practiced in Mixed Operations with Fractions and Decimals is put to work here in rewriting a ratio in whole numbers.