The courses are being funded and offered under the Department for Education and Skills' extended schools programme.
Pupils are being offered tips on what to wear, with a warning that low-cut tops, too much jewellery and make-up are inappropriate and may be misunderstood as a "come-on". They are told not to take boyfriends when they go babysitting and to agree the time employers should return home before taking on the work.
Careers advisers use role-play exercises to deal with fathers who place a hand on the babysitter's knee on the way home. Sue Rogers, the teacher who helped set up the course at Ralph Allen school, in Bath, said: "We advised that the girl should immediately lift it back off and tell him that it was inappropriate behaviour."
Last year, Ralph Allen successfully bid for pound;44,000 to run its extended schools programme for three years. The course cost pound;300 to set up and is free to pupils.
A school near Brighton runs a similar course, and other schools in the Bath area are consdering the idea.
Pupils learn how to market themselves as babysitters and St John Ambulance provides tips on dealing with medical problems such as cuts, bruises and asthma attacks. There is also discussion about rates of pay, which range from pound;4 an hour to pound;10 an hour, and advice on bedtimes.
Harriet Ridings, who is on the course at Ralph Allen, said: "I told the people I babysit for that I have done a babysitting course at school. They were really pleased."
But Alan Smithers, professor of education at Buckingham university, said the courses were a waste of taxpayers' money.
"There are some things in life that just require a little common sense and can be picked up by people going about their lives - it appears to me that babysitting is one such area," he said.
"This just seems to be attempting to turn something that people would naturally pick up into formalised learning. It appears both unnecessary and an ill-directed use of public money."
But John Dunford, general secretary of the Association of School and College Leaders, said: "Schools are supposed to be providers of social education.
"Young girls - particularly those who are doing vocational courses in things like childcare - would regard babysitting as useful experience. In that sense, schools are absolutely right to prepare them for it."