I spotted a headline the other week that highlighted how many zillions of pounds could be saved by introducing the "traffic-lights" system of teaching to all British schools. The method involves giving each child a green, red and amber card to display during lessons. If they grasp the point, it gets a green; if not, a red. The amber is for the vacillators.
The idea has actually been around for some time and is designed to give teachers instant feedback on who is understanding and who isn't. Now one pundit at least is selling it as some sort of universal panacea for the world of education, a wonder pill that you need only swallow to dramatically improve your teaching.
While it is aimed principally at schools, it occurred to me that it might also have some use in colleges. After all, we're all familiar with students who, for whatever reason, don't let you know when they're not grasping something. No harm in giving it a spin, I thought.
Before I took the plunge, though, I happened to mention it to a primary teacher I know. "It can work well," she said, "but there are a few drawbacks the enthusiasts tend not to mention.
"For a start, just because they've got cards to show, it doesn't necessarily mean that children who are fearful of revealing their ignorance in front of the class are going to be any more forthcoming. Safer to stick up the green and avoid the feared ridicule.
"Then there are always going to be those who aren't listening and just stick up any old card when asked. Bright kids, too, sometimes use it as a wind-up for teacher. You know that they understand, but still they'll hold up red and just sit there with a silly grin on their faces."
To tell the truth, I was getting a little discouraged by now, but there was more.
"Cards sometimes find their way into mouths for a bit of absent-minded chewing, which doesn't give them a very long shelf-life. And then kids get confused about which cards are theirs and which belong to their neighbour. If you're lucky, you can sort it out before they actually start hitting each other."
By the time she moved on to the colour blind and the army of support workers they need just to sort out which card is which, I cried, "Enough."
Universal panacea? I think not.