How many rupees does it take to make a busload of tourists feeling less guilty about trampling all over a school as part of their holiday?
The village of Achhnera was a sudden stop on the bumpy, hair-raising road from Agra to Jaipur.
It was a relief to escape the coach. Indian drivers make use of every inch of road space. This is easier to bear in congested town and city centre traffic, where everyone is moving so slowly that it matters little if there's scarcely the width of a postage stamp between you and the next vehicle or beast. On dodgy highways, there's the added excitement of daredevil overtaking manoeuvres and a worrying approach to speed.
But if the pause briefly made us feel safer, it was difficult not to wonder what right we had to be there in that school, poking our heads around corners, swanning in and out of classrooms and generally making our presence felt.
The kids, of course, saw things differently. It was the high spot of their day, and they clearly loved every minute of our visit.
They were also very well behaved, in sharp contrast to the demeanour of some of the urchins begging or hawking their unwanted merchandise at every routine tourist halt.
It was only later, when I looked at my photographs, that I spotted the stick clutched in hand whenever a teacher was captured on film. I hope it isn't the instrument by which that good order is enforced, but have my doubts.
On the question with which I began, the amount in our case was 6,500. That's roughly £80, and the whipround will be used towards the provision of ceiling fans.