I think that children rise to high expectations. Ie. if you expect a child to misbehave they will. However you also have to realistic.
For example my six year old son would not want to spend two hours sitting at table during long adult meal, but I would expect him to sit and behave himself for twenty minutes.
I am often guilty of having very high academic expectations. Its a balance between mentally stetching my son, without knocking his confidence with totally unrealistic expectations.