MP David Gauke swapped the Houses of Parliament for a market stall at the weekend to join students taking part in Small Business Saturday.
The teenagers from Berkhamsted School were taking part in the Young Enterprise scheme, where they have to run their own company for a profit.
The four firms taking part in the project are Ignite, Oxigen, Resolution and Hashtag HK. They made almost £600 between them from plugging their wares at Berkhamsted Market on Saturday.
Mr Gauke said: “It was great to meet lots of people who are really enthusiastic to learn about business and get some first-hand experience of it.”