Learning Japanese Particles

My grandson is trying to get to grip with Japanese particles.
Has anyone found any good book or way that they could recommend?
Currently he has "All about Particles" by Naoko Chino but could do with something with a bit more clarity.
How do young Japanese children learn these at school?
Any suggestions appreciated. Thanks

I've never been taught specifically about particles at school.
I think your grandson can't follow the way native kids learn them because native kids start learning the Japanese language as those who are already fluent in oral communication.

The best explanation about the difference between wa and ga, a typical pain-point in learning Japanese particles, I found in Making Sense of Japanese (What the Textbooks Don't Tell You) by Jay Rubin.
All in all, a very interesting read and recommended.