In our major subject science class, the students had been studying forces and motion, so they were given a challenge to build a rollercoaster using only paper and tape.
The focus was not only on demonstrating gravitational force but also on planning a course and developing skills in problem-solving and evaluating their initial designs to improve them.
They discovered that working from a plan helped them to visualize what their end goal would be.
In the first lesson, they almost gave up, but as soon as one student had a bit of success, it encouraged them to try again.
It was a fun challenge and students developed many skills.