One in five school girls won't put her hand up in class. The reason why is devastating.

Put up your hand if you’ve ever felt bad about the way you look.

Put up your hand if you’ve ever wanted to disappear.

Put up your hand if you’ve ever felt too unworthy to speak up.

Put your hand up. Because it seems that it is something that a significant number of young girls feel they can’t do.

This week, some important research was released that showed that many  young girls are reluctant to put up their hands in class.

And it’s not because they don’t know the answer to the teacher’s questions.

It’s not because they haven’t been listening.

It’s because they don’t want anyone to look at them.

A new report by the Centre for Appearance Research in the UK has revealed that one in five young girls will not put up their hand in the classroom because they are scared that people will look at them and pass judgement on their appearance.

Think about that for a second.

A young girl feels so self-conscious about the way that she looks that she feels like she can’t draw attention to herself in the classroom.

She feels so bad that she can’t participate in her education.

She hates how she looks so much that she can’t learn.

She’s holding herself back because she’s scared of what other people think.

The idea of even one girl feeling that way is terrible. But 20 in 100? That’s a sign that we are failing fundamentally in the way that we, as a society, are talking to our girls about how much they are valued – and how much they should value themselves.

That so many girls in 2014 have such a low self-esteem that they would put their perceptions of their appearance ahead of such a simple part of childhood as raising your hand is a disaster.

This isn’t just happening in the UK – the study had a total sample of over 49,000 girls and women aged 10 to 60 across five continents.

This is happening everywhere.

Now, there has been a lot of back and forth over the last week about whether the gender-specific toys that we buy are making our kids sexist. And there has been a loud lobby, particularly women, who have said that Barbie never hurt anyone.

That’s fine. We can call a truce about Barbie. But if, and only if, we start taking the issue of how girls feel about themselves (and our role in it) very, very seriously.

We need to take full responsibility for the fact that from an early age, girls are listening to everything that we tell them about how much we value their appearance. How much we like to do their hair and dress them up. How pretty, beautiful or cute they are instead of how brave, strong, kind and smart they are.

We are teaching girls to seek the admiration of the people around them, instead of teaching girls how much the world needs them and all of their talents: who they are, every day, regardless of what they look like.

Girls are taking these messages on board to the point that by the time they reach school, they don’t want to be looked at. They don’t want to ask questions. They don’t want to stand out. One in seven girls are so afraid of being judged on the way they look that they want to skip school all together.

The same Centre for Appearance Research study showed that these negative messages are being carried by young girls throughout their lives. At school and at university, women who think they are overweight tend to achieve lower grades. And a substantial number of adult women do not turn up to work or job interviews due to body image concerns.

This is something that we must stop early, or else it threatens to undermine the success and happiness of women throughout their lives.

So, today, put your hand up.

Put your hand up and show the girls in your life that they are valued for who they are.

Put your hand up and show every girl and woman around you that there is nothing wrong with being yourself.

Put your hand up and promise that you’ll never again miss an opportunity because you were worried about how you look.

Put your hand up to show that being brave, kind and smart is always more important than what anyone else thinks of you.

Put your hand up for our girls. Because if you don’t, then there’s a strong chance that they won’t ever do it for themselves.