One-to-One Tutoring vs Group Classes: What the Research Actually Says

Why tutoring has such a good reputation

In 1984 the educational psychologist Benjamin Bloom published a famous paper describing what he called the "2 sigma problem". In his studies, students taught one-to-one by a good tutor performed about two standard deviations better than students in a normal class. Put simply, the average tutored student did better than about 98% of the classroom students.

That result has been quoted for forty years. It's also widely accepted now that it was unusually high. Later research has found real benefits from tutoring, but nowhere near that size in most settings. So if someone tells you tutoring will transform your child's grades overnight, Bloom is probably where that claim started, and it's worth taking with some salt.

What the best modern evidence shows

The most useful recent evidence comes from large reviews that combine many rigorous studies.

In 2020, economists Andre Nickow, Philip Oreopoulos and Vincent Quan reviewed 96 randomised controlled trials of tutoring programmes. They found consistent, substantial benefits, with an average effect of 0.37 standard deviations. When the study was later published in peer-reviewed form, the updated analysis of 89 trials gave a somewhat smaller but still large average of about 0.29 standard deviations.

What does that mean in plain language? The poverty research centre J-PAL offers a helpful rule of thumb: an effect of 0.10 standard deviations moves a student at the 50th percentile up to about the 54th. An effect around 0.3 is roughly three times that, enough to move an average student noticeably up the class. In education research, that's a big effect. Very few interventions do better.

In England, the Education Endowment Foundation, which summarises evidence for schools, estimates that well-run one-to-one tuition can add up to five months of extra progress over a year, and small-group tuition up to four.

So tutoring works. But the details of these studies are where parents can learn the most.

The details that matter

Who the tutor is

The Nickow review found that programmes using teachers and trained paraprofessionals had larger effects than those using volunteers or parents. That doesn't mean only qualified teachers can help, but knowledge of the subject and of how to teach it makes a measurable difference.

How often, and for how long

The EEF's guidance notes that the biggest impacts tended to come from frequent sessions of up to an hour, over a period of six to eight weeks or more. Regular, focused sessions beat occasional long ones. A tutor once a month before exams is a very different thing from a tutor twice a week for a term.

Whether it connects to what's happening in class

Tutoring works best when it's aligned with what the student is learning at school, filling the specific gaps that are holding them back, rather than running a separate programme that never meets the curriculum.

Group size

Small groups can work well. The EEF found that effects drop noticeably once groups grow beyond about six or seven students. A "group class" of 25 is closer to an ordinary lesson than to tutoring.

So when is one-to-one better?

One-to-one tutoring tends to be the better choice when:

• Your child has specific gaps. If they missed a block of maths, never quite understood fractions, or struggle with essay structure, a tutor can target exactly that, without spending time on what they already know.
• Your child is shy or anxious. Many children never ask questions in a group. Alone with a patient teacher, they finally admit what they don't understand.
• The goal is close and specific. An exam in six weeks, a university admission test, an interview, a particular course.
• Your child is far ahead. Advanced students often coast in groups pitched at the middle. One-to-one lessons let them move at their pace.
• Their schedule is unusual. One-to-one lessons can fit around school, sport, religious study or time zones far more easily.

And when are group classes the better choice?

Group classes have real advantages that research on tutoring doesn't always capture:

• Cost. A small group can deliver much of the benefit at a lower price per child, especially for general practice.
• Motivation from peers. Some children work harder when others are in the room, and learn from hearing other students' questions.
• Social skills and discussion. Subjects like languages, debating and literature benefit from conversation with several people.
• Broad revision. When the need is general practice across a whole syllabus rather than fixing specific gaps, a well-run group can work very well.

Many families end up combining the two: a group class for regular practice, and a short block of one-to-one lessons when a specific problem appears.

Online or in person?

This question comes up constantly, and the honest answer is that the quality of the teaching matters much more than the format. Online lessons remove travel time, widen the choice of teachers dramatically and make regular sessions easier to keep. In-person lessons can suit younger children who find screens distracting, or subjects that need hands-on work.

For most school-age students with a decent internet connection, a good online tutor is a better choice than an average local one.

A practical way to decide

Ask yourself three questions:

1. Is the problem specific or general? Specific gaps point to one-to-one. General practice points to a group.
2. Does my child speak up in groups? If not, one-to-one will reveal far more of what they're thinking.
3. What can we sustain? Two shorter sessions a week for a term usually does more than one long session a week for a month. Choose a format you can keep up.

Then try it for six to eight weeks, the period where the research shows the clearest effects, and review honestly. Is your child more confident? Can they do things they couldn't before? Does their teacher at school notice a difference?

What to look for in any tutor or class

Whichever you choose, the same signs of quality apply. Look for teachers who start by finding out what your child already knows, who set clear goals you can understand, who give you short updates on progress, and who make your child do most of the thinking during the lesson. A tutor who talks for the whole hour isn't tutoring. They're lecturing an audience of one.

What tutoring can't fix

It's worth being honest about the limits, because a disappointed parent often expected tutoring to solve a problem it was never going to solve.

Sleep, stress and screens. A tired, anxious child who's up until one in the morning on a phone won't learn much in any lesson. Tutoring works best on top of reasonable routines, not instead of them.

A learning difficulty that hasn't been identified. If your child struggles with reading, attention or numbers in ways that seem out of proportion to their effort, talk to their school about an assessment. A good tutor may notice signs, but they're not a substitute for proper support.

A child who doesn't want to be there. Motivation matters. Involve your child in choosing the tutor or class, explain why you're doing it, and agree a goal together. Children who feel tutoring is a punishment tend to sit through it rather than learn from it.

Too little time between sessions. Most learning happens when a student practises what they were taught. Ask the tutor for short tasks to do between lessons, and make space for them in the week.

The bottom line

The research is clear that tutoring, done well, is one of the most effective ways to help a child catch up or get ahead. It's less dramatic than the old claims suggest, and it depends heavily on the tutor's skill, the regularity of sessions and how well they target your child's real needs. Small groups can deliver much of the same benefit for some children and some subjects.

If you'd like help working out what your child needs, you can tell us about your child and the subject, and our team will suggest suitable teachers for one-to-one lessons.

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