When a person is said to internalise a value, it simply means that those values have become a part of that person and it is integrated as part of his value system.
In schools, teachers try to internalise the good values in children such as respect, obedience, hard work, morality, etc.
A teacher or another adult can do this in a kid by teaching them how to say please when they want something, thank you when they want to show appreciation and sorry when they offer an apology.
Learners can do this by positively reinforcing good values and punishing bad values in children.
