It is probably safe to assume that the likes of Peppa Pig, Upsy Daisy and Thomas the Tank Engine have not completed initial teacher training. Neither does a school inspector’s remit extend to imaginary worlds. And yet many parents are convinced that the teachings of these, and thousands of other, television characters are beneficial for children.

This is understandable. Parents are keen to help their offspring prepare for school, so they rely on television and other electronic media, hoping that they will support children’s growth and development. And why wouldn’t they? The marketing around some children’s programming claims a myriad of educational and other benefits - and some parents even attribute learning to programmes when the makers have made no such claims. According to some, these shows are great for learning numbers, words, even new languages. And anyway, young children aren’t able to sit still for long enough to watch them too much, right?

Tune in to the evidence

Unfortunately, none of this is true. And teachers in primary schools need to educate parents and set the record straight if children are to fulfil their potential.

The research is compelling. A recent systematic review of TV use among children from birth to the age of 4 finds that it is harmful to children’s physical and mental health. Children who watch more TV tend to have a higher risk of being overweight or obese and to have poorer cognitive development for their age - including language development and the ability to pay attention, both of which are key to school-readiness. They also tend to have poorer psychosocial health and well-being, including issues with hyperactivity and self-control. The same review finds no evidence to suggest that TV could be beneficial to children’s cognitive development.

It is also clear from international studies that children watch more TV and spend more time using other electronic media as they age. This means that children who watch a lot when they are quite young will watch even more in middle and late childhood and adolescence.

Finally, a clear body of evidence now shows that watching more TV during childhood and adolescence is associated with a greater likelihood of being overweight, decreased fitness, lowered scores for self-esteem and pro-social behaviour and decreased academic achievement. Additionally, children and adolescents who watch more TV tend to watch a large volume when they are adults, too. The evidence for associations between TV-viewing and poor health in adults is almost incontrovertible. It has been linked to higher levels of depression, premature mortality, obesity and high blood pressure.

But how much is too much? UK government guidelines are vague but say that the use of electronic media should be limited for young children as much as possible. Advice from other countries, such as Canada and Australia, is more specific, recommending no more than one hour of electronic media each day.

No national estimates appear to exist about how often young children are actually using electronic media in the UK. However, international data suggests that most children spend more than an hour a day on this type of activity.

Time for a new schedule

Too much TV can clearly damage school performance. And if we are to take the transition from no school to school as seriously as the transition from primary to secondary, then schools have a responsibility to talk to parents about this when they enrol their children.

One practical suggestion is monitoring. It is one of the simplest ways to make sure that children spend an appropriate amount of time using electronic media. Some parents keep a simple diary on their fridge - with the child’s name down the left-hand side and times across the top. It is easy to fill in - just mark which child was using electronic media for which period of the day. Doing this over a couple of days and adding up the hours can be eye-opening. When my team advises parents to do this, many find that their children are spending about twice as much time using electronic media as they thought they were.

Switching off

It is also important to look at why parents let children watch so much TV in the first place. Many need to keep children safely occupied while they attend to various responsibilities - this is one of parenting’s great challenges. TV is often viewed as a great babysitter because it will hold children’s attention for a sustained period of time. In reality, other pastimes can just be as effective - for example, reading a book, playing with blocks, a train set or a favourite toy, or doing craft activities.

Admittedly, cutting down on TV time is not always easy. Schools need to let parents know that changing a child’s behaviour will not be a quick process. It will take persistence, and possibly a few unpleasant tantrums, to alter their habits. But many parents find that applying the new rules consistently can bring about change fairly quickly - often within a few days.

Teachers, too, may feel that this is a lot of work to cram into an already heavy busy schedule, but the relevant information can be presented easily enough in welcome packs when children’s names are put down for a school, and perhaps in welcome meetings, too.

It should also be seen as an opportunity. Schools can set out a framework of activities and resources that will not only provide an alternative to electronic media but also develop the skills and knowledge that prepare a child for school. This will ease the initial transition period and enable pupils to make better progress once they arrive.

It is important to note that I am not advocating turning off the television completely. Everything has its place and a little bit of high-quality programming is not going to leave a child lagging behind when school starts. But inappropriate viewing and watching too much is likely to have an impact.

So educators have an important role to play in informing and supporting parents on this topic. Many parents are unaware of the possible risks for their children and do not have access to the evidence. Schools can act as a conduit for information, leading to considerable benefits for all involved.

Trina Hinkley is a researcher in the Faculty of Health at Deakin University, Australia