Ted Wragg, professor of education at Exeter University, answers your professional problems, big or small, every week. Ask him for independent advice - or offer some of your own - by writing to: Dear Ted, The TES, Admiral House, 66-68 East Smithfield, London E1W 1BX. Or email: dear.ted@tes.co.uk

Ted says

A few years ago, some American schools got into difficulties with pupils who were Michael Jackson fans, because they banned the wearing of a single white glove. There were strikes and marches at the time, but it is no longer a live issue. It is not always easy to distinguish between passing fads and perfectly fair requests. Individuals can make decisions on the basis of naked power, but it is usually best to talk through issues with fellow teachers and maybe with children as well.

Schools can sometimes appear priggish to their pupils. Black stockings for girls and short hairstyles for boys are but two examples of what can be banned at one time - then become a requirement for another generation. Your own dilemma also raises the issue of consistency, as children are unhappy if one group is allowed something that another is forbidden, such as having access to the classroom at break.

Children managed in the past without water bottles, as they did without mobile phones. The latter are a real pest if they ring every five minutes, which is why many schools ban their use in the classroom. You need to decide whether or not water is a similar hazard. Beware of inconsistency, though. Some schools don’t allow boys to have long hair because they claim it is “dangerous”, when everyone can see that the same rule does not apply to girls, so this particular ruse fools no one.

Try discussing the matter with your colleagues, and perhaps with the children. They often need to see that there has to be a reason for rules, and water bottles may be fine in hot weather, but less essential at other times. Talking through behaviour issues is an important part of becoming a citizen. But then you must consider living with what you regard as another fad, if they manage to persuade you their request is a reasonable one.

You say

Liquid asset

I have had water bottles on desks in my Year 1 class for the past two years. After the initial novelty wears off, and children’s bodies have rehydrated (in about three weeks), their concentration increases, behaviour improves and the number of trips to the toilet reverts to normal. They change the water before registration in the morning, and refill their bottles during the day, if necessary; labelled sports cap bottles prevent loss or spillages. The only time I do not allow them to drink is during whole-class sessions on the carpet. If Year 1 can do it so can Year 5.

Katy Kowalska, Letchworth, Herts

A clever idea

I’m a busy English teacher who was becoming tired and lethargic halfway through the morning. My husband suggested I could be dehydrated, and that I should try drinking water during the lessons. The difference was almost immediate. I am now more alert and fresh - and no longer have a parched throat. When my students ask if they can drink water during my lessons, I actively encourage them to do so - the difference in their concentration and general wellbeing is visible. It may be a fad, but it is a clever fad.

Debbie Lebrett, north London

Definitely a fad

You are almost certainly correct in thinking this is a faddy trend. It seems incredible, but the fashion probably arose from a simple misconception that the amount of water the human body needs each day to function properly has to be taken in the form of drinks of water. No doubt bottled water companies have also had an influence. A host of newspaper and television stories and a clutch of educationists and politicians eager to embrace quick fixes have transformed a quirky idea into an unchallenged precept - a classic case of imperial novel attire syndrome.

If the theory were valid, one would have to explain why generations of schoolchildren around the world have managed to complete their school careers successfully without resorting to constant water-guzzling. If schools really want to make their students healthier, they should ban crisps, chocolate bars and fizzy drinks.

In any case, individual teachers should always be encouraged to resist faddy trends. If more of them had done so during the past few decades, we would now have a creative and dynamic education system, fulfilled teachers and more effective schools, instead of Hard Times revisited.

Phil Taylor, headteacher, Stamford high school, Tameside

What are the alternatives?

It depends on what drinking facilities are available outside the classroom.

Have you got a water dispenser with cold water and individual reusable cups? No need for bottles, then. Or, as is more likely, are you stuck with a couple of manky, frequently blocked water fountains where the pupils can queue all playtime for a few mouthfuls of warm water and germs? Wouldn’t you rather drink from a bottle? If bottles on desks pose a nuisance, a compromise would be to have them named on a tray in a corner where children could use them before and after lessons.

Jill Vale, supply teacher, Oxfordshire