Tournament of Minds is an international contest designed to enourage teamwork and creativity. 

Primary and secondary students from 18 different schools presented machines they had been working on for more than a month.

Machines were based on one of four categories they could choose from: applied technology, language literature, maths engineering and social sciences. 

Students had to design the machine, write a script to present their invention in an entertaining way and make costumes.

There is a limit on how much can be spent on materials and no adult participation is allowed.

Echuca East Primary School's applied technology team took on the challenge of designing wearable technology. 

The students invented a gadget worn on the wrist to help with homework and make snacks. 

Charlie Batchelor, 11, said the "swatch" was powered by bodily sweat that had an in-built computer to help with homework and the capacity to magically produce fruit and other goodies. 

For extra points the group made costumes out of newspaper and used an iPad to film themselves advertising their product. 

Teacher Tegan Parkinson said the tournament was a confidence booster for quieter students not involved in sport. 

Eaglehawk Secondary College's maths engineering team built a contraption that could process one kilogram of sugar and separate it into four equal amounts. 

"We spent every lunchtime we had to work on this," year 7 student Declan Watson said.

Before showing judges the machine, they performed a skit incorporating their creation. 

Teacher Casey Fry said not telling her students what to do was an opportunity for them to demonstrate creativity.

"It helps them develop independence," Ms Fry said.

Judges questioned the students thoroughly after their presentation to see who had come up with the ideas and which students had done what tasks. 

Winners from Saturday's central Victorian competition will be notified on Monday and will be invited to compete in the state finals.

Tournament of Minds also runs in Thailand, Hong Kong and New Zealand.