Here’s a technique I thought of to use when students observe that something a few decades back was “so long ago” that it is unimportant and irrelevant or, important both in Latin and Spanish classes, that slavery is an abstract idea and has little to do with our present situation:
I will ask the class if anyone in the class has a great-grandparent still living. Assuming a few will, I will then ask them if they think those people are a part of their lives, important to them, etc., even if they live far away. Most will respond affirmatively.
I will then tell them that my wife’s great-grandfather was a slave. True, she did not know him as he died before she was born, but that meant her grandfather had been raised by a man who had been a slave (not just born one, but had grown up as a slave).
I will then recount the story of my wife’s friend as an example of how some people do recognize the relevance of things that happened decades ago. After many years of friendship with my wife, she broke down and cried one day, revealing that she had always felt so bad about the fact that her grandfather had owned slaves. She recognized that that had little to do with her, but the fact that she had loved her grandfather gave her ties to a man that would have enslaved my wife. Only a generation or two separated my wife and her friend from being friends to being mistress and slave.