Class sizes in Practical Subjects


1. The longstanding convention – and NUT policy – that class
sizes in practical lessons should not exceed 20 has no basis in
law in England and Wales, neither is it explicitly set out in
DfES guidance.

2. The 1918 Education Act limited practical classes to 20 pupils.
The Elementary Education Code 1922 – Statutory Rules and
Orders 1922, No. 1432, made under Section 118 of the
Education Act 1921, Chapter 2 Paragraph 14, expanded on an
earlier regulation, and stated that:

“The number of children on the registers of any class in
Domestic Subjects, Handicraft, Gardening and other
practical subjects must not exceed 20, except that this
number may be increased to 40 in classes in Handicraft
provided that the class has at least 2 teachers if more than
20 children are registered”.

3. Regrettably, this legislation is no longer in force.
Regulations do exist in Scotland, where no practical class
(including science) may exceed 20 pupils [Schools (Scotland)
Code, 1956]. Similarly, in Northern Ireland, Regulation 15 of
the Secondary Schools (Grant Conditions) Regulations
(Northern Ireland) 1973 No 403 requires that practical class
sizes shall not exceed 20 where the pupils are under
instruction by one teacher. The Department’s guidance
recommends that a maximum of fewer than 20 pupils is
applied where there are pupils with special educational

4. In England and Wales, therefore, it is necessary to assimilate a
variety of guidance documents from a number of sources in
order to arrive at the ‘consensus’ of around 20 pupils per
practical class.


5. DfES documentation over the years has envisaged, in general
terms, a figure of 20 pupils – and certainly no more than 21 –
in an average sized design and technology classroom (roughly
100 sq m).

6. A 1985 Department of Education and Science Building Bulletin
No. 63 stated that for planning purposes, group sizes in design
and technology should be taken as 20 in KS3 and 15 at KS4.
Where rooms of less than 80 square metres in area are in use,
the recommendation for group size is given as 4 square
metres per pupil.

7. No new advice has been issued and this practice has
continued to be implemented in building design. Analysis of
the number of workplaces shown on drawings printed in past
DfES publications indicates that the maximum number of
anticipated pupils is approximately 20 per work area.

8. The 2000 edition of Building Bulletin 81 quotes 21 as being
the expected class size. The 2004 edition includes a chart
showing different numbers of pupils for rooms of different
sizes, which additionally takes into partial account the age of
the pupils involved. For example, the chart shows a room size
of between 95 and 107 square metres for a food technology
class of 20, and of 107 to 119 sq m for 20 pupils in a resistant
materials classroom. BB81 furthermore suggests spaces of
80-85 sq m for groups of up to 21 pupils doing small scale
practical activities such as textiles or graphics.

9. In the NUT’s view it is the nature of the activity and the
circumstances in which it is being undertaken that is
important. Although some activities are inherently more
hazardous than others, all practical activities can become
hazardous in some circumstances due to factors such as pupil
misbehaviour, poorly designed work areas, inexperience of
teachers and the ability of pupils.

10. In respect of science classrooms, DfEE “Safety in Science
Laboratories” 1996 states that “There is no statutory
limitation on class size in any subject in schools in England and
Wales. Teachers who are concerned that risks in practical
work are increased to an unacceptable level because of the
class size should report their concerns to the head of their
science department and, if necessary, their head teacher. It
may be possible to adopt alternative methods for particular
pieces of work. However, if risks cannot be made acceptable,
the activity must cease until it can be resumed safely.”
– para. 7.6 page 25.

11. It should be borne in mind that some local authorities will
have established their own rules about maximum class sizes
for science lessons. Laboratories in Hertfordshire, for
example, are currently designed to allow 2sq m free floor space,
excluding the area occupied by benches and cupboards, for
pupils aged 11-16 years. This is considered to be the amount
of space required for safe working. In laboratories with fixed
benches each pupil needs approximately 700mm of bench


12. In primary and middle schools, class sizes tend to be larger.
This automatically places limitations on the type of work
attempted, the amount of space available in the classroom,
and the ability of teachers/classroom assistants to intervene
and supervise effectively.


13. As far as special schools are concerned, the specific needs of
the pupils should inform the type of work carried out, and any
limitations on class size arising from the precise behavioural or
learning difficulties which the pupils may have.

14. The DfEE recommended the following dimensions for science
in special schools (from Building Bulletin 77):
45 sq m is sufficient area for 6-7 EBD pupils, 8 MLD or 6
physically disabled pupils. Or on a larger scale, 65 sq m is
sufficient for 8-10 EBD pupils, 10 MLD or 8 physically disabled

The Design and Technology Association (DATA)
and British Standard 4163

15. DATA advises that at KS3, class sizes of 20 should normally be
manageable, reducing to 18 at KS4. It furthermore suggests
that determination of class size will “require the exercising of
professional judgement by the head teacher and the subject

16. Another authoritative source of guidance is British Standard
4163 on safety in design and technology in schools: this states
that “the recommended maximum number of students in any
one work area is 21 students with one supervisor” (para. 3.1).


17. Regulation 10 of the Workplace (Health, Safety and Welfare)
Regulations 1992 states that “Every room where persons
work shall have sufficient floor area and unoccupied space for
purposes of health, safety and welfare”.

18. Encouragingly, the Advisory Code of Practice (ACoP) to these
regulations states that “The total volume of the room, when
empty, divided by the number of people normally working in it,
should be at least 11 cubic metres (measured up to three
metres from the floor). Unfortunately, in its accompanying
guidance for the education sector, the following caveat
“This figure does not apply to teaching areas, or meeting
rooms, kiosks or shelters”.

19. It should be borne in mind, however, that the Health
and Safety Executive (HSE) clearly indicates that it would
not hesitate to prosecute an employer if it believed
that overcrowding was a contributory cause of an

20. Teachers should be aware that under Section 7 of the Health
and Safety at Work etc Act 1974, employees are required to
take reasonable care for the health and safety of themselves
and others who may be affected by their acts or omissions at
work. This means that teachers can legitimately refuse to
participate in activities which risk their own health and safety
and/or that of their pupils. Advice should, however always be
sought from the NUT before doing so.


21. Ultimately, the best legally enforceable route down which to
go is for a thorough risk assessment to be carried out to
determine the available space, equipment, furniture, and from
thence the appropriate staffing levels and maximum pupil
numbers. A risk assessment will entail a careful examination
of hazards likely to exist, an assessment of whether the
particular hazards are likely to harm anyone and what
precautions need to be taken. Employers have specific legal
duties to carry out risk assessments for all areas of workplace
health and safety, and to appoint a ‘competent’ person or
persons to carry them out.

22. If the rooms are so designed that, as the teacher circulates
within the work area, a clear view cannot be obtained of all
working situations, it will be necessary to reduce the size of
classes. Supervision in work areas is complicated by the fact
that the teacher will occasionally need to obtain materials or
equipment from the store, where direct visual contact is very
likely to be impossible.

23. Inexperienced teachers need time and support in order to
develop the demanding skills required for the successful
delivery of practical lessons. A suitable ‘cap’ should be placed
on pupil numbers in practical classes taken by less
experienced teachers.

24. Where pupils clearly possess good self-motivation, capacity
for forethought, anticipation of hazards and a ready
understanding of advice and instruction, it is often possible for
them to be taught safely in groups of ‘official’ size.

25. Many pupils with SEN are at particular risk in practical
activities and this is an important factor when considering
group size. It is possible that those with statements of special
need will require additional support depending on the nature
of their learning difficulty. Where the range of abilities in a
class is very mixed or a high proportion of pupils have special
needs, class sizes should be reduced.

26. Decisions on class sizes might be influenced where
appropriate support staff can be timetabled to assist during
the course of practical sessions, for example with some
aspects of equipment use and the collection of materials from
stores and elsewhere.

27. In addition to maximising the safety and wellbeing of pupils,
there is a need to recognise the effect of class size on teacher
stress and to consider at what point this becomes a health
and safety issue – for both teacher and pupils. A significant
factor affecting the mental and physical health of a teacher
might be the mutually reinforcing effects of excessive stress
and pupils’ frustration caused by a lack of individual attention
in over-large classes. Teachers generally are aware of the
potential areas of danger in the classroom, and stress can be
caused by continually trying to identify and anticipate

28. It should be recognised that some equipment in design
areas can generate significant noise, thereby causing physical
stress when teachers are obliged to talk above the noise.
Checks should be undertaken to determine if the regulations
governing noise at work are being complied with. If
maximum exposure levels are exceeded, remedial action must
be taken – the simplest and most effective being class size
reduction. Teachers should be vigilant for signs of vocal strain;

NUT guidance on voice care can be found on the NUT website at

NUT guidance on noise at work can be found on the NUT website at

NUT class size policy is available at:

A report on t he impact of class size on teacher workload is available at: