He's very intellectual and loves numbers/letters.
My sister-in-law is a JK teacher and he would go once a week into her classroom and hang out with the JK's last year.
I started first showing him on his hand (using fingers) how to count/add.
Now he recognizes the numbers and can do simple addition/subtraction using either an iPad or pen/paper.
He's also able to write his name, my name, my wife's name and is little sisters name. (mind you it isn't the prettiest...LOL).
In our living room we have an eisle type thing with a huge white board and use dry erase markers.
My mom is also a retired JK teacher and usually does learning activities/things with him.
He is somewhat addicted to the TV so any chance we can get him away from watching NetFlix...we do.