Good manners
Please and thank you are not magic words
Many of us learned to remind children of the magic word. Say the magic word and you will get it. That works in the short term, but it turns courtesy into a trade. The child learns that this word opens doors.
I prefer a child to understand whom it is thanking. That is why I like to add the reason in everyday life. Thank you for passing me the bowl. With the reason, a formula turns into a relationship between two people.
The same is true for asking. Whoever asks acknowledges that the other person could also say no. That is exactly what makes a request polite, not the word itself. Children grasp this difference earlier than we give them credit for.