Should schools gorge on gadgets?

Want to see how equipping every child with a tablet can transform the way they learn? Want to meet leading tech firms which promise that their products are the key to your school's future? Then come to BETT, the educational technology fair in the vast Excel complex in East London.

But here's another thought - what if all of this is a huge waste of money which would be better spent on employing more teachers?

That was the provocative question posed in a blog on the eve of BETT by the General Secretary of the National Association of Head Teachers. According to one newspaper headline Russell Hobby said "money spent by schools on fad iPads could have funded 8,000 teachers". Another translated it as "Schools should stop wasting money buying iPads and 'shiny gadgets' for pupils."

When I caught up with Mr Hobby - on the phone rather than at BETT - he said his message had been somewhat exaggerated by those headlines. But he had wished to start a debate about the priorities for schools. "We're facing some very difficult spending decisions," he said, "we've got to ask ourselves, if we lost all the technology we have now would we actually go backwards?"

He insisted that he was no Luddite - "it's the uncritical purchase of gadgets that worries me," he said. I pressed him for an example and and he came up with interactive whiteboards, rather than tablets. These expensive pieces of kit are now in just about every classroom in the country, and Mr Hobby is far from alone in his criticism.

Plenty of teachers question their usefulness, and I have seen them employed in one school recently as surfaces on which to stick paper notices. Not exactly hi-tech…

I took these criticisms to the man who has probably done more than anyone to promote the use of technology in British education. Dominic Savage is the founder of BETT and the director general of the British Educational Suppliers Association, which represents the companies selling technology into schools.

"What an unfortunate message to be putting out," he said of Russell Hobby's attack on his life's work. We're asking teachers to do more and more every day. It's not a question of throwing teachers at the problem - it's asking how do we provide the technology that enables them to do what we are asking of them?"

I challenged him to defend the investment in those whiteboards and he admitted that these had not really worked. He said early users who'd had extensive training had produced good results, But then a cost-cutting exercise by BECTA, the now-disbanded school technology quango. "It does not surprise me in the slightest that it did not have the impact it should have, but it's not the problem with the technology in that case."

Where both men agree is that simply throwing money at technology without investing in teacher training does not work. And there's an issue of scale - bigger often isn't better. What often seem clever initiatives in a few well-funded schools then prove to be pretty useless when implemented wholesale by local councils or academy chains.

Still, with little money to fund the big technology schemes we've seen over the past two decades, the problem may be solving itself. While the major tech companies still turn up in strength at events like BETT, their stands seemed sparsely populated.

Creative teachers are turning to free software, cheap devices like the Raspberry Pi or even their pupils' mobile phones as they work out how to use technology to enhance their lessons. The digital transformation of education continues - but it's a much more decentralised and low-budget revolution.