Yes, I think the understanding with this lesson is that it's for teaching students the relevant meanings of these gestures in your native culture. Many times, at least in the Korean public education system, native English teachers are encouraged to introduce aspects of their culture. So the meaning in Brazil, Germany, Greece, etc. while although interesting and important, is probably not relevant in this lesson, unless you are teaching about those cultures. It is also important to note that these materials can be altered to suit the lesson.
