In short
- The fewest sessions you can run per unit is the number of pupils divided by your group cap, rounded up.
- Pupils' free times, teacher hours and rooms or devices decide how far above that floor you need to go.
- Research favours small groups for reading, but most of it studied struggling readers in intervention groups, not EFL reading sessions.
- Recount after every unit, because sign-ups and free times change during the year.
Run too few sessions and some pupils have no time they can make. Run too many and teachers spend hours in half-empty rooms. The right number comes from four figures you already have: how many pupils need the unit, the largest group you will teach, the times pupils are free, and the teacher hours you can give. This article works through the arithmetic with examples. It also reports what research says about group size for reading. That research is useful, but none of it was done in reading sessions like yours.
How many reading sessions should you run per unit?
Run the smallest number of sessions that seats every pupil without going over your group cap. Start by dividing the number of pupils by the cap and rounding up. That is the floor. Add sessions above the floor only when pupils' free times, teacher hours or rooms make the floor impossible.
- The floor: pupils divided by the cap, rounded up. 90 pupils with a cap of 15 gives 6 sessions.
- Time slots: each slot needs enough seats for the pupils who can attend only then.
- Teacher time: sessions multiplied by session length must fit the hours you have.
- Rooms and devices: a room with 12 desks, or 10 headsets for an online session, is a cap too.
These are planning rules from practice. Research on scheduling reading sessions is thin, and we found no study that tests how many sessions a reading unit needs.
Choose the group size first
The cap drives every other number, so choose it with care. Research on group size for reading exists. Most of it, though, comes from intervention for pupils who struggle, not from whole-class reading sessions.
| Source | Who and what | Finding |
|---|---|---|
| Vaughn et al. (2003) | Second-grade struggling readers, given the same extra reading intervention in groups of 1, 3 or 10 | Groups of 1 and 3 were both highly effective. Groups of 1 did better than groups of 10, but no better than groups of 3. |
| Education Endowment Foundation, small group tuition | Review of 62 studies of one adult teaching two to five pupils | Four months' extra progress on average. Effectiveness drops noticeably once groups grow beyond six or seven. |
| Education Endowment Foundation, reducing class size | Review of 63 studies of whole classes | One month's extra progress on average, from very limited evidence. Benefits seem hard to achieve until classes are smaller than about 20. |
| Blatchford, Bassett and Brown (2011) | 686 pupils in 49 primary and secondary schools, observed in class | In smaller classes, pupils received more individual attention. Engagement fell in larger classes, most of all for lower attainers in secondary school. |
The Education Endowment Foundation's toolkit entry on small group tuition adds a twist. As a rule of thumb, smaller is better. Yet in reading, small group teaching can sometimes be more effective than one-to-one or paired tuition, perhaps because pupils stay engaged as each takes a turn. The entry suggests that the quality of teaching may matter as much as the exact size of the group.
The EEF entry on reducing class size makes a similar point. Smaller classes help only if the reduced numbers let teachers teach differently, for example with better interactions and more feedback. Small reductions, such as from 30 to 25 pupils, are unlikely to be cost-effective. Blatchford, Bassett and Brown (2011) show what can change in a smaller group: pupils had more active interactions with the teacher.
What this means for your cap
A reading session is not an intervention group. Its job is to set up the story, let pupils read and check understanding. So the evidence does not hand you a number. The examples below use caps of 15 to 20, at or below the size where the EEF says smaller classes begin to show benefits. That is a planning choice, not a finding. For pupils who struggle, a separate group of three to five is closer to the evidence.
Worked examples
The table shows five invented grades. Each session lasts 45 minutes. Teacher time counts teaching only, not preparation.
| Example | Pupils | Cap | Floor | What free times and staff allow | Sessions per unit | Teacher time per unit |
|---|---|---|---|---|---|---|
| A. One grade 5 class | 26 | 15 | 2 | Every pupil can make either of two after-school slots | 2 | 1.5 hours |
| B. Grade 7, three slots | 90 | 15 | 6 | Some pupils can make only one slot. Pupils free at two times fill the gaps | 6 | 4.5 hours |
| C. Grade 9, online evenings | 60 | 18 | 4 | Most pupils are free on any weekday evening | 4 | 3 hours |
| D. Grade 8 with a support group | 75 | 18, or 5 for support | 4 + 2 | 66 pupils in main sessions, 9 weaker readers in two small groups | 6 | 4.5 hours |
| E. Grade 10, short of staff | 100 | 15, raised to 20 | 7, then 5 | Only 4 teacher hours a week, so the school raises the cap | 5 | 3.75 hours |
Example B, step by step (invented numbers)
Grade 7 has 90 pupils. The cap is 15, so the floor is 6 sessions.
The survey: 40 pupils can come only on Monday, 25 only on Wednesday and 15 only on Saturday. The other 10 can come on Monday or Wednesday.
Monday: 40 pupils need 3 sessions. That gives 45 seats, so 5 are spare.
Saturday: 15 pupils fill 1 session.
Wednesday: 25 pupils plus the 10 flexible ones would need 3 sessions. Instead, 5 of the flexible pupils take the spare Monday seats.
Wednesday now has 30 pupils, which fills 2 sessions.
Total: 3 + 2 + 1 = 6 sessions, exactly the floor. Without the flexible pupils, it would have been 7.
The lesson of example B is that pupils who can make more than one time are what let you reach the floor. So when you survey free times, ask for every time a pupil could attend, not just the one they like best.
Check teacher hours, rooms and devices
The floor assumes you have the staff and the space. Check three things before you publish the sessions.
- Teacher hours. Multiply sessions by session length. If the total does not fit, raise the cap a little, put two teachers in the same slot, or spread the unit over two weeks.
- Planning time. Every session for a unit can use the same plan, so the unit is planned once. Extra sessions add teaching time, not planning time.
- Rooms and devices. In school, the room caps the group. Online, count devices and headsets as well as seats.
Example E shows the trade-off. Raising the cap from 15 to 20 saved two sessions and 1.5 teacher hours per unit. It also took groups to 20. The EEF suggests that the benefits of smaller classes appear only below about that size. That is a choice to make knowingly, and to review after a few units.
Why the number changes from one unit to the next
Free times are not fixed. Sports seasons start and end, exams take over evenings, and holidays change family routines. A count that fitted in October may not fit in February. Treat the number of sessions as something you recount, not something you set once. The routine below is practice, not research.
- After each unit, list each session's sign-ups and attendance.
- Open a session where pupils were turned away or found no time they could make.
- Close or merge a session that has stayed well under the cap for two units, if its pupils can attend another time.
- Keep a small session when it is the only time some pupils can make.
- Survey free times again at the start of each term.
How Smarter Session Scheduling Can Cut Teacher Workload shows how merging small sessions saves teacher hours. Let Students Choose Their Session sets out the rules for sign-ups, caps and deadlines. If you open a new time, the test in Does Flexible Scheduling Improve Student Attendance? shows whether it raised attendance.
One large session or several small ones?
One large session costs the least teacher time. It works only if every pupil can make the same time and the group stays small enough to teach well. Several smaller sessions cost more hours, but they seat pupils whose timetables differ. The research above favours smaller groups for reading, especially for pupils who struggle.
For most grades, the practical answer is the floor: as few sessions as the cap allows, at times pupils can make. Whatever the size, the session itself follows the same plan. How to run an in-school reading session sets it out minute by minute.
How iRead handles this
In iRead, admins or teachers publish several sessions for the same unit, and each student joins exactly one, the one they can attend. An optimizer proposes the schedule that seats every student in the fewest sessions. The school's team reviews the proposal and approves it. Sessions run online or in school, and attendance is recorded automatically.
The core principle: Seat every pupil in as few sessions as your cap allows, at times they can make. Then recount after every unit.
See it in iRead: An optimizer proposes the schedule that seats every student in the fewest sessions, and the school's team approves it.
See how sessions workKey takeaway
The number of sessions per unit is arithmetic, not a rule of thumb: pupils divided by the cap, then adjusted for free times, staff and rooms. Choose the cap with the group-size evidence in mind, and recount as the year changes.
Frequently asked questions
How do you calculate how many sessions to run per unit?
Divide the number of pupils by the largest group you will teach, and round up. That is the minimum. Then check that each time slot has enough seats for the pupils who can make only that time, and that the total teaching time fits your teachers' hours.
What is a good class size for a reading session?
No study gives a number for whole-class reading sessions. The Education Endowment Foundation's toolkit suggests that smaller classes show benefits only below about 20 pupils, and only if the teaching changes. For struggling readers, Vaughn et al. (2003) found groups of three as effective as one-to-one teaching.
Should every unit have the same number of sessions?
Not necessarily. Sign-ups and free times change with sports seasons, exams and holidays. Recount after each unit. Open a session where pupils were turned away, and close or merge one that has stayed well under the cap for two units, if its pupils can attend another time.
Is one large session better than several small ones?
Only if every pupil can make the same time and the group stays small enough to teach well. Most grades have pupils with different timetables, so several sessions at the cap is the usual answer. Blatchford, Bassett and Brown (2011) found that pupils in smaller classes received more individual attention.
Sources
- Vaughn, S., Linan-Thompson, S., Kouzekanani, K., Bryant, D. P., Dickson, S., & Blozis, S. A. (2003). Reading instruction grouping for students with reading difficulties. Remedial and Special Education, 24(5), 301-315. doi.org/10.1177/07419325030240050501
- Education Endowment Foundation (n.d.). Small group tuition. Teaching and Learning Toolkit, Education Endowment Foundation, London. educationendowmentfoundation.org.uk/education-evidence/teaching-learning-toolkit/small-group-tuition
- Education Endowment Foundation (n.d.). Reducing class size. Teaching and Learning Toolkit, Education Endowment Foundation, London. educationendowmentfoundation.org.uk/education-evidence/teaching-learning-toolkit/reducing-class-size
- Blatchford, P., Bassett, P., & Brown, P. (2011). Examining the effect of class size on classroom engagement and teacher-pupil interaction: Differences in relation to pupil prior attainment and primary vs. secondary schools. Learning and Instruction, 21(6), 715-730. doi.org/10.1016/j.learninstruc.2011.04.001