Enterprising children made a splash outside Langley Fitzurse Primary School when they set up a water squad car wash.
When the seven and eight-year-olds needed money to go on a school trip, they decided to get out a bucket and sponge and work for it.
The primary school gave the children £5 and the class put together a business plan.
Headteacher Becky Harris said it was the children’s idea. She said: “It has really fired up their enthusiasm.”
The four boys motored through 25 car washes for drivers from the school and community and raised £150 towards a visit to Cadbury World in Birmingham.
Pupils have been learning about the Aztecs in Mexico, who were among the first people to make chocolate.
They should now be able to visit the attraction next month.
The boys said they were very pleased and surprised that their hard work had raised £150 from a £5 start-up.