Why does my cat want to bring live mice in the house to kill?

So, every once in a while my cat likes to bring live mice inside the house, so she can kill them in here. Why is this? I was told that sometimes cats try to teach their owners how to hunt, but I didn't get it from a very reliable source. Anyone here know why my cat wants to kill everything inside the house instead of just killing it outside and leaving it on the doorstep? (she does that sometimes, btw)