A piano uses a complex system of levers, hammers and strings to make sounds at different pitches. An electronic keyboard uses an entirely different electronic system to accomplish exactly the same thing.

Here's what we found when we took this one apart:

Each key is just a lightweight piece of plastic, molded to a larger plastic piece that joins three, four or five black or white keys. When you hit a key, the key moves downward and the plastic bends a bit. This pushes on a rubber button that presses a tiny metal tab on a circuit board under the keys. The tab is a tiny switch - pressing it completes a specific circuit on the circuit board. This circuit board connects to a larger, central circuit board.

The central circuit board is a basic computer. Like the circuit board in just about any electronic machine, it connects a collection of microchips, transistors and resistors. The control panel buttons work just like the keys - when you press down on one, it completes a small circuit on the circuit board. This sends a signal to the microchips.

So, when you press either a key or a button, you're sending a message to the keyboard's computer. The computer's job is to create electrical signals that move the keyboard's speakers to make particular sounds. The computer has hundreds of electrical signals stored in its memory, and each signal represents a unique sound.

Each speaker is made up of a flexible cone, called a diaphragm, and an electromagnet. The electrical signal from the computer drives the electromagnet up and down, which moves the attached diaphragm in and out. The moving diaphragm pushes and pulls on air particles around it. Those air particles push and pull the particles around them. This creates tiny moving waves of air pressure called sound waves. These waves push your eardrum back and forth, and your brain recognizes the movement as a sound.

And here's how it all comes together:

Moving a speaker diaphragm back and forth more quickly or more slowly changes the frequency of the sound wave. We hear a higher frequency as a higher pitch and a lower frequency as a lower pitch. We recognize each distinct pitch as a different note.

When you press a particular key - say the "middle C" key - the computer brings up one particular electrical signal pattern from its memory. That electrical signal fluctuates at just the right speed to make the speaker create the exact pitch of middle C.