Before your child can use equivalent fractions: the 3 things they need first (Class 5)
Equivalent fractions need three earlier ideas: a fraction seen as one quantity rather than two numbers, multiplication understood as equal groups, and factors. The rule "multiply top and bottom by the same number" is easy to follow and easy to follow without believing. A child who follows it without believing it stalls in Class 6.
What equivalent fractions actually requires
This is one of the quietest breakages in primary maths, because the procedure is so simple that children get it right for years while holding a completely different idea underneath.
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What a fraction actually means
Class 4
Equivalence is the claim that 1/2 and 2/4 are the same point on the number line. If a fraction is still a pair of numbers rather than a position, "the same" has nothing to attach to, and the child hears a rule about digits instead.
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Factors and multiples
Class 5
Going the other way — simplifying — is finding a common factor. A child who cannot quickly see that 12 and 18 share a 6 will simplify in several small steps, lose track, and often stop one step early.
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Multiplication as equal groups
Class 4
Multiplying top and bottom by 3 means cutting every piece into three. If multiplication is only a table that has been memorised, that sentence is meaningless, and the rule stays a rule.
How to check in five minutes
Ask on paper. Listen to the reasoning rather than the answer — a right answer here tells you very little.
Which is bigger, 3/4 or 5/8? Tell me without working it out.
"3/4, because 3/4 is 6/8." The conversion is used as a tool to compare sizes.
"5/8, because 5 and 8 are bigger numbers." The fraction is being read as two whole numbers. This is the fundamental gap and it is extremely common.
I have 1/2 of a chocolate bar. My friend has 2/4. Who has more?
"Same." Said immediately, with no calculation, possibly with a look suggesting it was a trick question.
"My friend — he has two pieces and I have one." Counting pieces while ignoring their size. A child can simplify fractions fluently on paper and still answer this way.
Why does multiplying the top and bottom by the same number not change the fraction?
Anything about cutting each piece into more pieces without changing the amount. "You've got more bits but they're smaller" is a complete answer.
"Because you do the same to both." A restatement of the rule, not a reason. Worth probing once more before concluding — some children know it and cannot yet say it.
The three ways children get this wrong
What to do if there's a gap
If your child read 5/8 as bigger than 3/4, stop working on equivalence and spend a week on fractions as positions. A paper strip folded in half, then quarters, then eighths, with the folds marked, does more in ten minutes than a chapter does. The goal is that they can point to roughly where 3/4 sits before they can calculate anything about it.
If the gap is factors, that is arithmetic fluency and it responds to short, frequent practice rather than explanation.
Reading a fraction by its digits rather than its size is the same confusion that makes negative numbers hard a year later, where −5 gets called bigger than −2 for exactly the same reason.
If the only gap was the third question — they could not say why the rule works — that is the least urgent of the three, but it is the one that decides whether dividing fractions makes sense next year.
Questions parents ask
My child can simplify fractions but still says 2/4 is smaller than 1/2. Why?
Because simplifying is a procedure on digits and comparing is a judgement about size. They are stored separately until a child sees a fraction as one quantity. The procedure being fluent is not evidence that the idea is there.
Is it enough if my child knows the times tables?
Times tables make the arithmetic fast but do not supply the idea. Equivalence is the claim that two different-looking fractions are the same point on the number line. A child can multiply top and bottom by 3 perfectly and still not believe the result is the same number. This is the difference we describe in understanding versus pattern-matching.
When does this actually start to matter?
Class 6, when adding fractions with unlike denominators arrives. That topic is equivalence used four times in a row. A child who is shaky here will appear to have suddenly become bad at maths in Class 6, when nothing has changed except the load.