M3.4.2 For the adult
Ratios and fractions
Ana mixes juice and water in the ratio 2 : 3. Is the juice two thirds of the drink?
What this chapter teaches
The numbers in a ratio count parts. Adding the parts gives the whole, so each part is a fraction of the whole. A ratio compares part with part and a fraction compares part with whole.
Three questions to ask
There is no one right wording. Listen for the idea.
- In the ratio 2 : 3, how many parts are there in all?
- Why is the juice two fifths of the drink and not two thirds?
- How would you turn the fraction two sevenths back into a ratio?
After the chapter, the learner can
- Change a ratio of 2 : 3 into fractions of the whole
- Tell a part to part ratio from a part to whole fraction
What they copy into their notebook
A ratio compares part with part. A fraction compares a part with the whole. Add the parts to find the whole. In 2 : 3 the whole is 5 parts, and the first part is 2 out of 5.