Lancashire armed response officers and a police dog unit apprehended the youth in Preston last night.
An officer later tweeted a photograph of the weapons and tools they had seized from the teenager, along with an exam-style caption.
"Night before an exam do you: A. Revise to better your future prospects. B. Revise because that's what your parents and/teachers tell you to."
Or, joked the police, "C. Take out weapons and tools to burgle and get yourself nicked."
The correct answers, according to the officer, were, "A and B."