This is not really an activity, it's more like a poster or a handout about the origins of the names of the week days. You can use it as a filler or as you wish. You may also point out that the English language has strong roots on the Norse culture, that's how most of the days of the week got their name (apart from Sunday, Monday and Saturday - the last one being the name of a Roman god). I'm a real Mythology freak, so I think this is an interesting subject to discuss! I hope you enjoy it!