Simple Systems vs. Simple Machines

I am a third grade teacher. I am confused about a TEK we are supposed to teach in science. It talks about simple systems like a toy car or a yo-yo. It says nothing about simple machines, like levels and pulleys. But the only lessons I can find are about simple machines. Can someone tell me if simple systems is just a stepping stone to simple machines or am I actually supposed to be teaching simple machines?

Thanks for your help!

Mrs. Notpit