What components make up a simple sentence

What effect is created by the plaque posted on the gate at the entrance to the family's home in nadine gordimer's "once upon a time"? the words written on the plaque offer readers a foreshadowing of the story's outcome without revealing the actual conclusion, the author's use of flashback allows readers to understand what is at the heart of the issues of encroachment in the suburban neighborhood the repetition of the words written on the plaque presents an oxymoron because readers already sense that the plaque has been ineffective in warding off intruders. the author introduces a paradox in which readers are presented with a warning notice when no actual infraction has taken place.

American history (is, are) studying the american colonies.

How do i correct this sentence correctly?