Where is the line between Protection and Deception?

In Billy Collin's "The History Teacher", a history teacher tries to protect the innocence of his students by hiding the truth about all the crude and imperfect events in history. This history teacher had good intentions, but the poem also explains that the students--the innocent children that the teacher is trying to protect--are already bullying other kids on the playground and therefore are not innocent at all. This poem is ironic because, by lying to the students, the teacher is hurting them more than he would if he told them the truth. When he covers the events of the past, the children don't know that conflict can lead to war and destruction, and therefore think it's ok to bully. This same concept of lying to protect the innocence of a group of people is used by Dimmesdale in The Scarlet Letter. Dimmesdale conceals his affair with Hester from his congregation in order to protect their view of the Puritan church as good and Holy. If he told them what he did, the congregation would lose their faith in religion and stray away from it. Dimmesdale lied to protect them from the flaws in human nature, but by lying he only denies them the knowledge of their worst enemy: their own flaws in character. The congregation should know that no one is perfect, but they idolize and come to believe in something that doesn't exist: a man without flaws. The poem also reminds me of 1984 by George Orwell, in which the government not only lies about the events in history, but completely rewrites them. In 1984, the government controls everything and no longer lies to protect the people, but lies to protect the government itself. This is the extreme of a lie with a good intention, and what the lies in "The History Teacher" could escalate to in an extreme case.