Our children all keep a half-litre water bottle on their desks. We introduced this four years ago when we began looking at approaches to learning.
We had two training days with accelerated learning guru Alistair Smith, who advocates taking account of a variety of learning styles. Our teachers also had training in "brain gym" - brief physical activity sessions designed to stimulate the brain.
At the same time, we asked children to bring in water bottles. The thinking is that drinking water improves the way the brain works, that it keeps you alert. And it certainly does wake the children up - they are on task. And they're not constantly interrupting classes by asking to go to the water fountain.
There was apprehension when we introduced the idea. Some teachers were worried that the children would have to nip to the toilet all the time, or that they would spill water. And I thought they would use the bottles as water pistols. Miraculously, none of these things happened.
It appears that drinking water helps with behaviour. I have no evidence of this, but it does seem to keep our pupils going through the afternoon without the angry outbursts we used to have.
I think children now are more comfortable in the classroom, and if they're more comfortable they're going to work better. The constant interruptions of children continually asking to go out for a drink upsets the flow of the lesson as well as the children's concentration. It also helps teachers to keep control if the children are cooled by the water and getting on with their work.
When new parents came in for next year's primary 1 in June, I told them about our arrangement and they were very supportive - and intrigued. In our nursery we have a water cooler and give the children water, too; they're too small to manage a bottle on their own.
We have good test results but it's really down to the children who come here; we have a good catchment area, and the children come from homes where education is considered important. So I can't say that we've got fabulous test results because of the water. But having plenty of drinking water so readily available has really been of benefit.
I'm not saying we don't have trouble here, either. But I think there's less trouble because of the immediate access to water.
Kirsty Jack is headteacher at Corstorphine primary school in Edinburgh. Interview by Martin Whittaker