But education and parent teacher groups criticised the survey by North Yorkshire County Council, which contained more than 100 questions - half of which were about drugs and drug abuse and 26 others about sex.

BBC: Schoolchildren quizzed on drug habits

The research, based on the US-wide National Education Longitudinal Survey, found that a teacher's gender had "large effects on student test performance".

BBC: NEWS | UK | Education | Male teachers 'better for boys'

The government said the reading check had been supported by three-quarters of parents questioned in a survey by the National Confederation of Parent Teacher Associations.

BBC: Education & Family

No nationwide survey of the insects' numbers has been published since former RAF pilot and school teacher Bob George, who began mapping them in the 1950s, published his Atlas of the Fleas of Britain and Ireland in 2008.

BBC: Who, What, Why: Have flea numbers jumped?

Asked by YouGov, which conducted the survey, who parents most trusted with their children's education, 59% opted for their head teacher, while 6% said the education secretary.

BBC: Teachers urge parents to back action

In Araioses, the poor town visited earlier in this survey, schools get 1, 600 reais a month direct from the ministry, and their parent-teacher associations decide what to spend it on.

ECONOMIST: Start at the beginning