Passers-by could be forgiven for thinking there was a revolt at Huddersfield University when students started firing missiles at lecturers.
But it was all in the name of education.
First-year engineering students were set a practical challenge to design and build a siege engine - a medieval war machine used to storm castles.
They pretended that the Huddersfield Narrow Canal running through the Queensgate campus was a moat and a painted cardboard sheet was the castle wall.
The enemy was one of the lecturers keeping a close eye on whether or not the missiles hit their target.
The students came up with various types of siege engines - catapults, ballistas and trebuchets - with which to fire their shots.
The idea came from tutor Tony Johnson. He wanted to test the students' knowledge of mechanics, velocity and acceleration.
"The purpose was to generate enthusiasm and a bit of fun and pull together what they have learned," he said.
"Doing practical exercises like this helps them to apply theory to practice.
"At the end of the day we are in the business of training people for jobs."
The students enjoyed the exercise - regardless of their success.