Explain in simple terms that speakers convert electrical signals into sound waves and screens use patterns of light to display encoded information.
A speaker is a device that turns an electrical signal into sound. Inside every speaker is a small cone connected to a magnet and a coil of wire; when an electrical signal, carrying a pattern, runs through the coil, it makes the cone vibrate rapidly, and that vibration pushes the air into the sound waves you hear.
A screen works with light instead of sound. It is covered with an enormous grid of tiny lights called pixels, each one able to turn on, off, or glow a certain color. A picture on a screen is really just a giant, fast-changing pattern telling each pixel exactly what to do, similar to the 1s-and-0s codes from a couple weeks ago, just spread across thousands of tiny points instead of one signal.
Mastery looks like: They can describe, in simple terms, that a speaker turns an electrical pattern into sound through a vibrating cone, and a screen turns a pattern into light using pixels.
Common stumbles: Thinking sound comes directly from electricity with no physical vibration involved; assuming a picture on a screen is one single image rather than a pattern controlling many tiny separate lights.