What are systematic errors?

A systematic error is like when your ruler always measures things a little too short, not because it's broken, but because it has a tiny habit.

Imagine you're drawing shapes on paper with a ruler that’s slightly off. Every time you measure something, it looks shorter than it really is. You might think the shape is perfect, but actually, it's just a little bit squished, and everyone else who uses the same ruler would have the same problem.

A systematic error happens because of something that’s always there, like your special ruler. It could be a messed-up clock, or a scale that adds 1 pound to everything you weigh. No matter how many times you use it, it always messes things up in the same way.

If you know your ruler is always short by half an inch, you can just add that extra bit when you measure, and suddenly everything looks right again! That’s how scientists fix systematic errors too. They find out what's wrong and then adjust for it.