We clean a safety outflow valve, install a stall strip and talk about studying to be an aircraft mechanic.
CORRECTION! A stall strip INCREASES the speed at which a wing stalls. Here is a description from a commenter. Sorry for any confusion.
“The stall strip actually PROMOTES a stall, allowing it to stall at a lower angle of attack. It is mounted usually at the root to allow the wingtip and ailerons to remain effective during a stall.”