What is a short summary of the story, Generational Differences, from the collection, Afterparties?

In the story, Generational Differences, a mother writes an account from the past for her son. She recalls the tragedy she witnessed in 1989 while teaching at Cleveland Elementary, and how this event also impacted her son. At the end of her account, she tells her son that he does not have to carry all of her pain. He must simply understand that they are survivors.