I created this activity after many years of teaching native Spanish speakers in my Spanish classes who would say that certain words were "not right" because the words that we were learning in class were not the same as the ones that they used at home.
To remedy this, I created a story and wrote two different versions. One is in American English, and the other is (to the best of my ability) in British English.
First, I give the students the British English version of the story and have them read through it. Then, I hand them the list of words from the story. I ask them to work with a partner to see if they can figure out what the words on the list would be in American English. After they finish as many as they can I give them the American English version of the story to read.
After this activity we talk about how the same language can be different in different parts of the world. With this activity the students now understand that just because I teach a word that is different than what they are used to, we can still both be right.