Why can't my child concentrate, and how long should they actually be able to?
Almost every parent asking this has, in the back of their mind, a comparison to an adult's attention span - and that comparison is the single biggest reason a perfectly ordinary child's concentration looks like a problem. A child's ability to sustain focus genuinely grows with age, in a fairly predictable, well-documented way, and expecting a seven-year-old to sit still through a twenty-minute homework session the way an adult might is not a reasonable baseline - it is simply not yet within reach for most children that age, regardless of effort or discipline.
There is a widely used rule of thumb among child development professionals: a reasonable expectation for focused attention is roughly two to five minutes per year of age, for a specific, structured task - so a six-year-old might reasonably sustain twelve to thirty minutes on something engaging, while a ten-year-old might manage twenty to fifty. This is a rough guide, not a hard rule, and it varies a good deal by child and by how interesting the task actually is, but it is a far more useful anchor than an adult's own concentration as the implicit comparison.
The rest of this post sets out a fuller table by class and age, separates concentration in class from concentration on homework - because they are not quite the same skill, and a child can be fine at one and struggle with the other - and works through what genuinely helps versus what wastes effort, before covering when a concentration problem is worth a closer professional look rather than a home routine change.