Dense liquids, parachutes, and carbonated drinks used to blow up a balloon were part of the experiment display at The Hills Grammar School's year 4 science fair.
The experiments were designed and conducted by the school's 45 pupils who are part of the International Baccalaureate Primary Years Program.
Year 4 teacher Alison Star said the program's inquiry-based approach to education inspired pupils and showed their strengths.
They spoke confidently as they presented their work to parents at the science fair on Friday.
"They have wanted to work through their lunch hours to get their projects up and going which is really sweet," Mrs Star said.
"They have come up with the concepts themselves. It gave them the real opportunity to tap into their own interest and explore that in detail."
Year 4 teacher Margie Raymond said pupils were guided through the scientific process to understand aims, hypotheses, methods and results analysis.
"We've done a number of experiments through the six-week unit of inquiry to guide them and get them to think about the things they'd like to investigate, so this is a culmination of their investigations," she said.
"The beauty of it is it can be totally open. You'll see some very different experiments.
"Because we were testing properties of materials, like absorbency, flexibility, elasticity, magnetism and states of matter it leant itself to a wide variety of things that they could do."
Pupils Samara Mundi and Piper Cassidy used scales, open air and their taste buds to test which of brown, green or ripe yellow bananas had the highest sugar content.
"We predicted that the brown banana would have had the most because it was really heavy," Piper said.
Samara added: "We knew that the starch would develop into sugar."