Why this happens
If your child says "I understand it, I just can't do the questions," they are describing a real and specific gap, not laziness. Understanding a concept lives in one part of learning; executing a multi-step calculation under time is a separate skill that only builds through practice.
Most of the breakdown happens in a few predictable places.
Where calculations go wrong
- Rearranging the formula. Your child knows the equation but freezes when the unknown is not by itself.
- Units and conversions. Centimetres left as centimetres, or grams not converted to kilograms, quietly wreck an answer.
- Standard form and the calculator. Powers of ten and calculator entry cause slips even when the method is right.
- Multi-step questions. Each step is doable, but stringing four of them together without losing track is the actual challenge.
- Not writing the working. Skipping steps hides mistakes and loses method marks.
How to close the gap
The fix is not more theory. It is structured, repeated practice on the mechanics of solving.
- Start with one topic and do many similar problems, so the pattern becomes automatic.
- Insist on a fixed routine: write the formula, list what is given with units, rearrange, substitute, then calculate.
- Have your child explain each step out loud. If they can narrate it, they own it.
- Build up slowly from one-step to multi-step questions rather than jumping straight to hard ones.
The role of confidence
A lot of "I can't do calculations" is really "I freeze on the page." When a student has a reliable step-by-step routine, panic drops and accuracy rises. Success on a few full questions often unlocks the rest.
When one-to-one helps most
This particular gap responds very well to one-to-one teaching, because a tutor watches the pen move and catches the exact step where it breaks, whether it is the rearranging, the units, or the calculator. That is hard to spot in a large class. If a few weeks of practice at home is not moving things, a focused calculation-skills session can make a quick difference.