"A teacher snack shamed a kid. I say, good on her."

I was at my son’s primary school sports day a couple of weeks ago when I heard a teacher calling out, “I can’t believe you’ve brought a bottle of soft drink along to an athletics carnival!”

I looked. There was a kid, who looked to be about nine or so, gulping fizzy drink from a bottle. He just grinned at the teacher.

A lot of people get upset about the idea of teachers snack shaming kids. “It’s up to the parents what their kids eat,” they say. “Let the parents decide. It’s none of the teacher’s business. There might be reasons why parents feed their kids what they do.”

Well, could someone who sends their kid along to primary school with a bottle of soft drink please justify it to me? I mean, seriously. Tell me why you think it’s okay.

A quarter of kids in Australia are overweight or obese. Our society agonises over why. Junk food ads on TV. Misleading labelling on food. Overprotective parents driving their kids to school. What the mother ate before conception and during pregnancy.

Well, here’s another reason: Parents are putting crap in their kids’ lunchboxes.

It’s not just soft drinks. My son comes home and tells me that other kids get a packet of chips in their lunchboxes every day. He wants to know if he can have a packet of chips every day too.

Well, no. He can’t.

I understand it can be hard to get kids to eat healthy food. I understand it can be confusing to know what's healthy. Fruit-flavoured drinks, snack bars, sugary cereals. There are things that are promoted as good for kids that actually aren't the best options. But surely everyone knows that soft drinks and chips shouldn't be part of a kid's daily lunch. Don't they?

When you send a kid along to school with soft drinks and chips, you're giving them the message that these foods are part of a normal, healthy diet. You're setting up eating habits for a lifetime.

Clearly, there are parents who don't think there's anything wrong with it. Hard to believe, with all the nutritional advice we're constantly being bombarded with, but it's true.

That's why I do think it's okay for teachers to step in. It is okay for teachers to snack shame. Well, not actually "shame" kids, obviously, but point out that what they're eating isn't good for them. Someone has to do it.

Here's a Sunrise story on childhood obesity. Post continues after the video.

Why do I care about other people's kids? Because, in the short-term, they're making my kids think it's okay to eat crap. Because, in the long-term, my taxes are going to have to pay their medical bills.

I'm not going to pretend that I bake zucchini muffins for my son's lunchbox, or give him six different types of raw vegetable plus a dip. But I do pack him a sandwich on wholemeal bread and some fruit and a bottle of water.

Really, it's just as quick and easy to stick a banana in a lunchbox as a packet of chips. And tap water is way cheaper than soft drink.

To that teacher who called out the kid for guzzling soft drink at 10am on a school sports day... good on you.

Do you think it's okay to send kids to school with soft drinks and chips?

Jane Olivier Lea, a primary school art teacher and mum of two, trawls the internet for quirky, funny cartoons, jokes and sayings. She then replicates them on brown paper bags for her sons, aged 12 and 13, to make them smile when it's time to eat their lunch at school - and they'll make you smile too. Check them out for yourself ...

(Jane Olivier Lea can be followed here on Reddit. All pictures courtesy of Lea's Facebook page - "My Son's Lunchbag Drawings".)