At this stage, your child is becoming more open to new modes of learning. Fortunately, he's fit to play board games now, which is a perfect way he can boost his cognitive skills! The best thing about board games is that they are age defined. You have amazingly constructive board games that are tailored particularly for a age group.
What you need to know
Board games make a child learn a lot. This is because, most board games have specific rules that the child need to understand and follow. Board games need skills that include a lot of understanding. This propels the child to think beyond his limits. Board games also teach kids a lot of patience and how to play sitting in one place. While there might be issues when the child loses to an opponent, which must be dealt with positively, board games are an excellent way to bond with friends and family.
What you need to do
If you haven't yet, introduce your child to board games that he would be interested to play. Help him learn the game and if possible play with him. (For eg. Let me know what you understand from this game, Ali. Can we both read the rules and figure out what needs to be done?). Allow your child to explore and understand. Don't stop his thinking, instead encourage him to come up with his own understanding of the game. This will hone his cognitive skills and help him mature in a positive way.