The brilliant way this mum taught her "entitled" 13-yo son a valuable lesson about money.

Recently, US woman Cierra Forney made a disturbing realisation about her 13-year-old son.

He had began acting a little “entitled” and was making “snarky” comments about other students at his school who couldn’t afford to buy brand-name clothes and had to buy their outfits from Wal-Mart or op-shops.

Not wanting to tolerate her son’s behaviour, Cierra decided to teach him a valuable lesson… and she shared the whole thing on Facebook.

“Today, he took his own $20 to the Goodwill (a second-hand store) to buy clothes to wear the entire week to school,” Cierra shared, in a post that has since been shared over 226,000 times.

“Whatever he found is what he would have to wear. He isn’t happy and shed a few tears but I firmly believe in 15 years he will look back and laugh at the day his mom made him shop at Goodwill.”

Cierra said she wanted to teach her kids that “money isn’t everything”.

“If you have to degrade other people because of where they shop, then you too will shop there,” she shared.

Other parents were quick to praise the lesson, telling Cierra she deserved a “mum of the year” award for her smart approach to the problem.

LISTEN: One in seven Aussie kids think cash from the ATM is free money. On This Glorious Mess, we discuss why they don’t understand money. Post continues after audio.

“Thank you for setting a great example for other parents on respect, humility, compassion, and financial responsibility,” one mum wrote.

Another shared: “Good for you…It seems that your son is a very sweet boy who just lost sight of a few things for a minute.”

But some were critical of Cierra’s approach, commenting that her 13-year-old son’s ‘entitled’ attitude must have been learned from the example set by his parents, a sentiment that prompted Cierra to write a response.

"I didn't do this to punish him. It wasn't to show him that Goodwill isn't a good place to shop. I did this to teach him that money and name brands don't change who we are as people," she wrote.

"He can still be the amazing, adorable, loved kid that he is WITHOUT the expensive stores!"

She also added that she realised she and her husband were partly to blame for his "expectancy of always having name brands".

"[We] had our son when we were VERY young. We always strived to give him all the things we never had and because of that, he has grown to expect these things," she wrote.

She also added that she asked her son's permission before sharing the story online, and said they have an amazing relationship.

"I SOLEY did this to help my son become a better man," she shared.

"All that matters is my son is completely 100 per cent okay with what happened. My son has learned a valuable lesson from this AND my son is rockin' his button up shirt he bought from the Goodwill with PRIDE today!"