There may be a simple explanation about why some children feel tired and lethargic during the afternoon at school.

It's not that they're lazy or ill. It's because they have not got the habit of drinking enough water for their needs.

Certainly there has been a marked improvement at St Andrew's School in Hove since it started a policy of letting children bring water bottles into the classroom.

Now many other primary schools have followed suit, all with beneficial results. Secondary schools are also beginning to warm to the idea.

The children feel brighter and are able to tackle their work with more energy. This helps the teachers too.

Water costs nothing and this is a scheme every school in Sussex should be encouraged to adopt.