Learn about Time and Distance
Many Olympic events are races. Some races are short and require quick bursts of speed, while others are longer and require more stamina. Watch some races and notice the distance that the racer has to go.
You can also pay attention to the timer. The sporting events use very exact timing down to the millisecond. What does a millisecond mean?
In the Olympics (as in most of the world) distance is measured using the metric system. Learn how big is a centimeter, meter, and kilometer. Make some measurements and try to see if you can run some races. How fast can you run?