I am going to disagree with you. The beginning when you are teaching them to read is "let's look it up". You also wants to do this because, especially as they get older and the words more complex, you maybe wrong. The word excise can mean to cut something out when you are using it at a verb but it can mean a tax when used as a noun.
The next step is "what did it say when you looked it up?" If they are reading books that are from other countries the word may mean something entirely different there.
In this case by telling him to look something up she found that he really did not know how. It she had just answered she would have blithely kept sailing along not knowing that a crucial part of his education was neglected.
Perhaps we agree. The key word is “let’s.”
Too often I see parents dismiss frequent questions and conversation from children. The kids learn that they can’t be bothered. They go elsewhere for information and basic communication and that is not ideal.