Coaching 爷爷 and 奶奶

Since 爷爷 does not know how to play the game, I had to be the coach and teach him .... 奶奶 joined in later and I had to do the explanation again ... but how come 奶奶 kept saying she did not understand even though I spoke in simple Mandarin ??? Hmm ....

Daddy was giggling at the side ....