MYP Maths: Fractions FAQ

Read what operation is actually being asked — add, subtract, multiply or divide — before touching the numbers. Find a common denominator for adding or subtracting, convert mixed numbers to improper fractions first, and always simplify your final answer. Show each step; MYP Criterion A rewards clear mathematical reasoning, not just a correct final number.

Find the lowest common multiple of both denominators, convert each fraction to an equivalent fraction with that denominator, then add or subtract the numerators only — never the denominators. Simplify the result at the end. This is the single most tested fraction skill across MYP 1-3 assessment tasks.

To multiply fractions, multiply the numerators together and the denominators together, then simplify. To divide, flip the second fraction upside down (find its reciprocal) and multiply instead. Convert any mixed numbers to improper fractions before starting either operation.

Addition combines quantities of the same size, so the pieces must be equal size first — that's what a common denominator gives you. Multiplication scales one fraction by another; it doesn't need matching pieces because you're combining a fraction of a fraction, not stacking equal parts together.

Divide the numerator by the denominator to get a decimal, then multiply by 100 for a percentage. Going the other way, write the percentage as a fraction over 100 and simplify, or convert a decimal to a fraction using powers of 10 as the denominator. MYP 1-3 assessments regularly test all three forms in one question.

Fractions are hard because they break the pattern kids learn with whole numbers — bigger denominators mean smaller pieces, and the same rules from multiplication don't carry over to addition. In fifteen years of teaching this, the students who struggle are almost always the ones who never really understood what a fraction represents, not just the mechanics of manipulating one.

Forgetting to find a common denominator before adding or subtracting is the single most frequent error I mark. A close second: not simplifying the final answer, which loses marks under MYP Criterion A even when every calculation step is correct.

A fraction is fully simplified when the numerator and denominator share no common factor other than 1. Find the greatest common factor of both numbers and divide each by it; if the only shared factor left is 1, you're done.

Fraction fluency underpins algebraic fractions, probability, and rates work in MYP 4-5, and directly feeds into IB Diploma Mathematics: Analysis and Approaches or Applications and Interpretation, where students simplify rational expressions using the same denominator rules. Weak fraction skills at MYP 1-3 tend to resurface as algebra mistakes two or three years later.

Consistent, varied practice beats memorising rules in isolation — mixing word problems with pure calculation questions helps students see when to apply which operation. On RevisionPrep, MYP Mathematics Topical Worksheets and Revision Notes cover fractions with the graduated difficulty MYP 1-3 students need before moving to MYP 4-5 content.

Criterion A (Knowing and Understanding) assesses whether you can correctly select and apply fraction operations to solve problems, including in real-life contexts. Criterion B (Investigating Patterns) is less about single fraction calculations and more about recognising number patterns — for example, exploring what happens to a fraction's value as you repeatedly halve it.

Most students who still struggle at this stage never secured the conceptual foundation in MYP 1 — they learned steps by rote rather than understanding why a common denominator is needed. This isn't unusual, and it's fixable with targeted practice rather than simply repeating the same worksheet-style drills.

Use everyday contexts — cooking measurements, splitting a pizza, discounts while shopping — to make fractions concrete before drilling abstract calculations. Regular short practice sessions (10-15 minutes, a few times a week) beat one long weekend cram, and checking their working step-by-step catches misunderstandings early rather than after a test.