Researchers recently investigated the relationship between extrinsic rewards (cash prizes, trips and so on) and performance at school (behaviour, attendance and results). There were exactly no gasps of surprise in Bennett Mansions at the news that there was barely a limp handshake between the two.
But schools still beggar themselves. I've seen iPads, driving lessons and even cash waved in front of students like bits of apple before a parrot.
Research into motivation in the workplace is nothing new. A common finding is that reward schemes work up to a point, as long as they are short - no longer than a month - and have a clear goal.
But this is for adults. How much shorter should a scheme be to work for children? Annual competitions may sound wholesome but they lose the majority of children after the first week, leaving only the die-hards and obsessively competitive to play the field.
Worse still are schemes that require groups to participate collaboratively. Imagine being a good kid in a class of yahoos, watching the reward train pull further and further away. Why bother?
Then there are the reward schemes that punish the good. Many schools operate a points system that encourages desired behaviours. But who needs the most encouragement? The wayward. So who gets the most points? The same. At the end of the year you can see the Bash Street Kids rocking up to Chessington World of Adventures as the compliant kids look on sadly, wondering why they got out of bed.
The danger with reward schemes is that they dislocate behaviour from the intrinsic reasons behind it. If children are good only because they accrue extrinsic benefits, the prize becomes the aim. The spoonful of sugar replaces the medicine, but without the power to heal.
The message sent to children is corrosive and dangerous: learn and win a treat. But the real prize is the learning. If students can't see that, they should be taught it, by teachers and schools explicitly valuing education, openly and unashamedly.
The problem with cash rewards in particular - apart from the fact that they are ghastly - is that behaving well becomes an option rather than a moral duty. If the imperative is hypothetical rather than categorical, anything is possible.
Rewards will never be enough to motivate everyone and the focus of children can't be guaranteed for the desired amount of time - two years is a millennium in the mind of a child. And those schemes that focus on loss aversion (where children start with a notional cash bonus and lose it as they accrue sanctions) are toxic to the relationship of trust a teacher needs to have. Imagine the disputes as teachers wield the power to actually take money from their students. What a horrible scenario.
No, the best reward remains, as it always has, the honest, sincere and proportionate praise of a teacher whose opinion the student values. It's simultaneously priceless and cost-free. And it can't be bought.
Tom Bennett teaches at the Jo Richardson Community School in Essex and is director of the ResearchED conference