Table 1.

 Reasons why schools were excluded from the study (n=33)

Reason	No of schools
Private school	22
Single sex state school	4
Pilot school (mixed sex state school)	1
Mixed sex state school with no sex education until year 11	1
Mixed sex state school in which sex education is taught in small groups throughout the year*	3
Mixed sex state school that closed before the study began	2

^*Excluded because at any one time pupils in a particular year group would be at different stages of sex education.