Before your child can work with negative numbers: the 3 things they need first (Class 6)
Negative numbers need three earlier ideas: a number line read as positions rather than counting, subtraction understood as the distance between two numbers, and place value. Most difficulty here is not about negatives at all. It is that for six years, a bigger digit meant a bigger number, and nobody told the child that rule has been withdrawn.
What negative numbers actually require
This is the first topic in school maths where a rule children have relied on since Class 1 stops being true. That is what makes it hard, and it is why extra practice on negatives often does not help.
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Reading a number line
Class 4
Not drawing one — reading one. A child who thinks of numbers as a counting sequence starting at 1 has nowhere to put −3, because you cannot count backwards past the beginning. A child who thinks of numbers as positions simply carries on to the left.
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Subtraction as difference, not take-away
Class 4
"Take away" cannot survive here: you cannot take 9 away from 4 in a take-away world, which is exactly why children say it is impossible. "How far apart are they, and in which direction" works for every case, including 4 − 9.
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Place value with decimals
Class 5
Ordering −2.5 and −2.05 needs both place value and direction at once. Children who are fine with whole negatives often fall apart here, and it reads as a negatives problem when it is a decimals problem. It is the same digits-versus-size confusion that shows up in equivalent fractions.
How to check in five minutes
Draw a line on paper, mark 0 in the middle, and ask these.
Which is bigger, −5 or −2?
"−2, it's further right" or "−2, it's closer to zero." Answered by position.
"−5, because 5 is bigger than 2." The minus sign is being treated as a label attached to a number rather than as part of where the number is.
It is 3 degrees. It drops by 7. What is it now?
"−4." Ideally counted down through zero out loud, or pointed to on the line.
"You can't" or "4". Zero is being treated as a floor. This is the take-away model of subtraction still in place.
Why does 5 − (−3) give 8?
Anything about distance or direction. "It's how far apart 5 and −3 are, and that's 8" is a complete answer.
"Two minuses make a plus." A rule with no meaning behind it. It works for two years and then produces sign errors all through algebra.
The three ways children get this wrong
What to do if there's a gap
Draw the line, every time, for a few weeks. Not as a teaching aid to be outgrown — as the thing the numbers actually are. Ask "where is it" before "what is the answer". Most of the repair here is replacing a mental picture, and a picture is not replaced by being told it is wrong.
If the gap was the temperature question, the work is on subtraction rather than on negatives. Ask difference questions with positive numbers first — "how far is 4 from 9" — until "how far apart, and which way" has replaced "take away" entirely.
Do not drill signed arithmetic while the underlying picture is wrong. It produces a child who is fast and confidently wrong, which is harder to unpick later than a child who is slow. The same pattern shows up in what a variable actually means a year later.
Questions parents ask
Why does my child think -5 is bigger than -2?
Because they are comparing 5 and 2 and treating the minus sign as a label rather than a position. For six years, bigger digits meant bigger numbers. Negative numbers are the first time that rule fails, and nobody tells the child the rule has been withdrawn.
Is the temperature analogy good enough?
It is good for ordering and for addition. It breaks down for multiplication, because multiplying two temperatures means nothing. Use it to establish order, then drop it rather than stretching it.
My child is fine with negatives but keeps making sign errors in algebra. Is that the same problem?
Usually yes. Persistent sign errors in Class 8 are almost always an unfinished Class 6 idea, not carelessness. The tell is whether your child can explain why subtracting a negative adds, without reciting a rule about two minuses. We go into this in understanding versus pattern-matching.