'Real knowledge is to know the extent of one's ignorance'- Confucius
If the father gets up early morning and does puja in the morning, by seeing that the children also learn how to perform puja and he will also do that. Instead of that the gets up very late and have his bed coffee and then go for the bath. The child thinks that this is the way we have to do and he will follow the same way. By simple teaching something, the child will not learn. Follow what you want to teach, the child will follow you.
Parents should take care of their child and see that they are on the right path. Then they will never get attracted for other bad habits. So follow and teach.