Cadbury has been criticised by campaign group the Food Commission for offering free sports gear in return for vouchers from chocolate bars. It is the latest in a long line of companies to give equipment to schools. BBC News Online looks at what's in it for them.
Walkers crisps run coupon promotions for free school books
It has become an annual ritual for many schools.
Bins are set up in classrooms and day by day for three months they fill up with the millions of vouchers collected by mums and dads from shopping trips to Tesco.
The school then turns them into thousands of pounds worth of computers - 3,600 of them last year.
Like the Cadbury sports equipment promotion, the scheme has government backing because it promotes learning and fills in technology gaps the state cannot afford to fund.
So the schools and ministers are happy but what about the company?
It hopes its largesse is rewarded with "brand awareness", says Simon Mahoney, of sales promotions firm SMP.
"Cadbury is hoping that when parents are buying chocolate, they'll recognise theirs as the one the school is collecting and choose it," he said.
"These kind of promotions give products added value without cutting price.
"It's a tried and tested formula to make people buy more."
At its conference last week, the National Union of Teachers described schemes like the one from Cadbury and a similar one by Walkers crisps for free books for schools as "frightening".
Ian Thompson, a teacher from Gloucestershire, said: "It is nothing more than marketing to our children in the name of education.
"It involves selling saturated rubbish to the people we teach."
But schemes like those of Walkers and Cadbury are not aimed at children, said Mr Mahoney.
And they have been scrutinised by the Institute of Sales Promotion, the industry's self-regulating body, of which Mr Mahoney is vice president.
"These are aimed at what we call the 'gatekeeper' - mum or whoever does the family shopping.
"They're the ones who make decision about which brands to buy.
"I don't think children would be swayed by the offer of free maths books."
In America, commercialism has reached the point in schools where companies sponsor maths books and there are Coca Cola machines on every corner.
"It won't happen here," Mr Mahoney said.
"We have strict rules and regulations in the UK governing targeting children with advertising - it's got to be educationally beneficial and the head teacher has a veto."