Law of large numbers

Okay kiddo, imagine you have a bunch of marbles in a jar. Each marble could be either red or blue. If you shake the jar and pull out one marble, it's hard to know whether it will be red or blue. But if you keep shaking the jar and pulling out more and more marbles, eventually you'll start to see a pattern. It's more and more likely that you'll get about half red and half blue, because that's roughly how many red and blue marbles are in the jar.

Now let's zoom out and think about a bigger picture. Imagine the jar now has millions and millions of marbles, and you keep shaking and pulling them out until you've looked at all of them. The same thing happens as before: if there are roughly half red and half blue marbles in the jar, then you'll end up with roughly half of each color. This is the law of large numbers.

What this means is that when you have a lot of data, it becomes more and more accurate. This is why scientists and mathematicians and other smart folks like to collect lots and lots of data when they're studying something. They know that if they have enough data, they'll start to see patterns that are more and more likely to be true. And that's how we learn new things about the world!