Keep it simple and visual. A good beginner-friendly approach is to explain exposure as controlling how much light reaches the image: shutter speed is how long light comes in, aperture is how wide the opening is, and ISO is how sensitive the camera is to that light. Analogies can help—for example, filling a glass with water: shutter speed is how long the tap is open, aperture is how wide it’s opened, and ISO is like using a smaller glass that fills faster.

Use lots of example photos. Show:

• the same exposure made with different shutter/aperture combinations
• underexposed vs overexposed images
• fast shutter freezing motion vs slow shutter blur
• wide aperture for blurred backgrounds vs narrow aperture for more depth in landscapes

If possible, do a live demo with cameras in manual mode. Start from a correct exposure, then change one setting at a time so they can see the effect:

• stop down aperture and observe the darker image / deeper depth of field
• raise ISO and compare brightness and noise
• slow or speed up shutter and compare motion blur

Then introduce semi-automatic modes as a practical next step. Avoid too much jargon or too many concepts at once; focus on helping them connect the numbers to visible results.