This is really cool. Out of curiosity - how did you actually set this up for him to use? Was it on tablet or a computer or phone? Any suggestions for a dad of a 3.5 year old?
Also, is he reading / at what level? Trying to get a feel for when I can introduce it to him.
Also, is he reading / at what level? Trying to get a feel for when I can introduce it to him.