Addition and subtraction word problems
Solve word problems involving addition and subtraction of fractions with like denominators, using visual models and equations
What a learner can do afterwards
- A jug contains 3/4 litre of juice; 2/4 litre is poured out — how much remains?
- Two pieces of ribbon are 2 3/8 and 1 5/8 inches — what is their total length?
- Draw a fraction model to represent and solve a fraction word problem
The lesson
A word problem tells a story with numbers hidden inside it. Your job is to find the fraction equation the story is describing. Look for clue words. Words like 'left' or 'poured out' usually mean subtract. Words like 'total' or 'altogether' usually mean add.
Two pieces of ribbon measure 2 3/8 inches and 1 5/8 inches. The word 'total' means add: 2 3/8 + 1 5/8. Add the whole numbers first, 2 + 1 = 3. Then add the fraction parts, 3/8 + 5/8 = 8/8, which is 1 whole. So the ribbons together measure 3 + 1 = 4 inches.
Once you spot the clue word, write the fraction equation first. Then solve it the same way you already solve mixed numbers: whole numbers with whole numbers, fraction parts with fraction parts.
Turn the story into a fraction equation using the clue words, then solve it the way you already know how.
Watch it
Where it sits
Learn first
This opens up
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.