While there is no clear evidence from research linking class size to pupils' attainment, large class sizes lead to a reduced range of teaching strategies in science because of safety considerations.
Smaller groups give the teacher a chance to employ a far richer variety of teaching strategies and give the pupils the opportunity to be much more actively involved in their learning.
Safety concerns can limit pupils' activity. Science teachers have to carry out a risk assessment to judge the appropriateness of any particular activity for the size of class. It is inevitable that the direct involvement of individual pupils will be more limited in larger classes. The more passive pupils become, the less their enthusiasm for science will grow.
The Association for Science Education recommends a maximum class size of 20 for practical activities for pupils aged five to 16. We would urge that serious consideration is given to implementing this in schools.
JANE WHEATLEY Chair-elect Association for Science Education College Lane Hatfield, Herts