A black box is a mechanism that someone knows the function of, but not how it works. Locks surround us. We know that if you put the right key in a lock and it will open, but most people don't understand the mechanisms in any more detail. Today in 5th grade we learned how the driver pins, key pins, springs work together to allow the barrel to turn when aligned at the shear line. It turns out the lock is not looking for a key, but rather the specific combination of crenellations (bumps) cut into the key. Alternatively, we can put a small amount of tension on the barrel of the lock and bump each pin up until we find one under tension and trap it in place, then move on to the remaining pins. Either way it is the same result - an open lock.
This skill is easy to master with a clear lock, but picking up the very subtle tactile feedback in the tools through one's fingertips takes, calm, focus and patience. We want students to leave class after this lesson seeing locks in the world as simple mechanisms they now understand - in the mind's eye they see clear locks everywhere - not black boxes. Our students will shatter glass cealings, now they also see every door as open and thier own choice to go through it or not.