Why does Todd also get low marks in the history subject?

In Apt Pupil (1998) the head master says to Todd:

Head Master: even your strongest subjects History, You went from a solid "A" to a "C" minus.

Todd Bowden always spends time with Arthur Denker (who is a famous history person), since he met him. But Todd got low marks in all subjects including History.

Then why did Todd also get low marks in the history subject?

plot-explanation apt-pupil

Best Answer

Because of his obsession with Denker he neglects his studies.

US High School History is an extensive subject and although Denker was old there is no indication he was continuing to teach Todd anything.

Instead, Todd..

forces Dussander to share disturbing stories of what it was like working at Nazi extermination camps, and how it felt to participate in genocide.

Denker's knowledge of that specific era would have been on point but only cover a very brief period in history.

Note that also, this situation is not permanent, Denker forces Todd to improve his grades.

To complicate things even further, Todd even purchases an SS uniform from a costume shop, and forces Dussander to wear it. When he spends more time with the old man, his grades suffer, he loses interest in his girlfriend, and he conceals his bad grades from his parents. In turn, the Nazi blackmails the young boy into studying to restore his grades, threatening to expose the boy's subterfuge and his dalliance with Nazism to his parents.