What are some good academic lessons I can teach to a child going into the 5th grade?

I have a cousin who is on the lower side of the IQ scale and I would like to help her before she goes into 5th grade. As of now, she’s on the lower end of the 3rd grade reading scale, she doesn’t know her multiplication very well, and she’s very hard to get to.

What kind of fun but educational things can I do with her? She gets easily frustrated and tired, so I’d like to help boost her morale and teach her while having as much fun as possible.

Please help. I’m bad with children.