Grandma Wants Me To Teach Her English---assignment For Me

Hello Nairalanders,
This might be funny to you but its real and true. My grandma has given me an assignment to teach her english, she is sitting for the upcoming NECO GCE, the problem is i dont have any idea of where i'd start from, so please anyone with the idea where i could get a book and where do u suggest i start from, i have been looking text books but i dont know the right one, please anyone who knows which text book to use please reply, i have even bought IT=IT, IF=IF AT=AT.
This is just the work of this fucking ASUU strike.
Abeg make una reply