Teaching young students about MLK Day is very important, yet it can be difficult to explain to students how things used to be long ago when there was segregation. Read this blog post for some great ideas.
I would use this activity to help students get an idea of where they actually are in regards to the bigger idea that they live in a house, on a street, in a city, in a state, in a country and so on. This is helpful for students to actually get it so that it makes sense on their level. You could also do this on a smaller scale first of the school so they get an idea before the large scale project that this is.