Even though you might have Windows or Mac computers/laptops in your home, you can still have it run much of the same software that's used on the school's computers.
Why might you want to do that?
Well, a big reason is compatibility... If you use the same software at home as is available at school, then you won't need to worry as much about whether your teacher would be able to open the file (e.g. a document) that you created at home.
Most of the software used at school is available at no cost, so you (or or your parents) wouldn't need to spend extra money.