Phi Learning — WorldWiseKids
Mathematics

Fractions, Decimals & Percents

Parts of a whole, how to combine them, and the three ways to write the same amount.

3 lessons in this unit.

Learning goals
  • Name the numerator and denominator and say what each one means
  • Build equivalent fractions by multiplying top and bottom by the same number
  • Compare two fractions and decide which is larger
Key ideas
Numerator / denominator
Top = how many parts you have; bottom = how many equal parts make the whole.
Equivalent fractions
Multiply (or divide) the top and bottom by the same number and the value doesn't change: 12 = 24 = 36.
Common denominator
Rewrite both fractions over the same bottom number so they're easy to compare or add.
Worked example

Which is larger, 23 or 34?

  1. Find a common denominator. The smallest number both 3 and 4 divide into is 12.
  2. Rewrite each: 23 = 812 (×4 top and bottom) and 34 = 912 (×3 top and bottom).
  3. Now the bottoms match, so just compare the tops: 9 > 8.
Answer:34 is larger.
Teaching tips
  • Fold paper strips into halves, thirds, and quarters so the learner can SEE that 24 and 12 cover the same length.
  • Watch for the classic mistake: a bigger denominator means smaller pieces, so 18 < 14.