This project proved to be a great favourite amongst students.
The original idea came from a Sheffield Hallam University project but I modified the circuit and the housing to make it into what became a Year 8 design project at the time.
The circuit is the same as the Joule Thief shown here - https://sites.google.com/sheffield.ac.uk/diamond-electronics/3-building-and-testing-circuits/the-joule-thief .
The project was basically a garden light for the summer time, when it goes dark and a fair wind is blowing it creates a glowing effect which we made into garden decorations.