My son is watching me do chores and not helping me, it's making me angry.
Why isn't your son helping you do the chores?
I expected him to pitch in and help but he hasn't.
If you expect him to help with the chores, you have to tell them that. As a child, he may not have the same reasoning skills as an adult and is unaware that you expect help.
I've told him I need him to help with the chores before but he seems to be ignoring me.
As his parent, you need to tell him to help. He may have forgotten so a helpful reminder and instructions of what to do would make sure he helps you.