Adding and subtracting with different denominators
Find a common denominator, then add or subtract.
Planned. This module is part of the plan and is not written yet.
Why it matters
A builder who uses half a bag of cement on one wall and a third of a bag on another needs to add 1/2 and 1/3 before buying more.
Draft outline · in review- For
- Level 5–6 · Primary 5 to Primary 6
- Inside
- 5 lessons and a test · about 75 minutes
- Topic
- Fraction operations · core, 2 of 4
Inside the module.
5 lessons in order, about 75 minutes in all, then a short test. Learners go at their own pace; the minutes are a guide, not a timetable.
Draft outline · in review
Lesson 1: Why denominators must match
See with strips why halves and thirds cannot be added as they are.
Explain10 min, from minute 0
Lesson 2: Finding a common denominator
Use the lowest common multiple of the two denominators.
Worked example15 min, from minute 10
Lesson 3: Adding and subtracting
Rewrite both fractions, then add or subtract the numerators.
Practice20 min, from minute 25
Lesson 4: Mixed numbers
Add and subtract mixed numbers, regrouping when the fractions pass one whole.
Worked example20 min, from minute 45
Lesson 5: Review
Mixed questions, with feedback on each.
Review10 min, from minute 65
End-of-module test
Find common denominators, and add and subtract fractions and mixed numbers with different denominators.
Mastered at 85% or more. Retake it until you pass; nothing is lost, and each try gives feedback.
Already know it? A Challenge Test (planned) clears the whole module: 90% overall, no objective below 75%.
Last stageafter about 75 min
Practicalities
Draft outline · in reviewBuilt to run offline
Planned to run on the Lantern's own computer, with no internet needed.
Languages
Planned first in English; every module aims to reach all of the Lantern's languages.
Try a question.
One question from the module, as a learner would meet it. Have a go, then open the worked solution a step at a time.
Draft outline · in review
Ama's family uses 2 1/2 kg of maize flour one week and 1 2/3 kg the next. How much is that altogether?
Work it out on paper first, then show the answer and mark it yourself.
Particulars
Where it sits
Maths · Fractions, decimals and percentages · Fraction operations
What a learner can do after it
- Find a common denominator for two fractions.
- Add and subtract fractions and mixed numbers with different denominators.
Needs first
Unlocks
Nothing requires this module yet.
Suggested before
Level
Level 5–6 · Primary 5 to Primary 6
Level mappings are approximate. A qualified teacher or lecturer in each country must check them before they appear in the app.
Difficulty for its level
2 of 4 · Core
Time
About 75 minutes
Alignments
- Aligned to Common Corefull · in review5.NF.A.1
- Aligned to NERDCpartial · in reviewNERDC Primary 5–6 Mathematics: addition and subtraction of fractions (descriptive ref)
Alignment in review until a qualified teacher or lecturer checks it. No exam body, university or vendor endorses us; learners still sit the real exam.
Challenge Test
Planned: a Challenge Test to prove you know it and skip it. Pass at 90% overall, with no objective below 75%.
The route here.
Everything this module builds on, drawn as a route from its foundations. Solid lanes must be mastered first, or cleared by a Challenge Test; dashed lanes are suggestions that never lock anything.
- MA-FDP-FRS-01Parts of a wholeMaths · Primary 2 to Primary 3 (Level 2–3) · Sample lesson in the demoTry the sample lesson: Parts of a whole
- MA-FDP-FRS-03Fractions on a number lineMaths · Primary 3 to Primary 4 (Level 3–4) · Planned Needs Parts of a whole (required).
- MA-FDP-FRS-04Equivalent fractionsMaths · Primary 4 to Primary 5 (Level 4–5) · Planned Needs Fractions on a number line (required).
- MA-FDP-OPS-01Adding and subtracting with the same denominatorMaths · Primary 4 to Primary 5 (Level 4–5) · Planned Needs Fractions on a number line (required).
- MA-FDP-OPS-02Adding and subtracting with different denominatorsMaths · Primary 5 to Primary 6 (Level 5–6) · Planned · the destination Needs Adding and subtracting with the same denominator (required), Equivalent fractions (required).
Help light the room where this is learned.
Every route on this map starts in a classroom with 24 stations, a tutor that works offline and a facilitator upstairs. Four are planned and waiting for light.