To get across the idea of word formation, write up the word ANTIDISESTABLISHMENTARIANISM on the board and ask students what they can tell you about the word. ‘It’s long,’ may be all you get. But ask them what type of word it is (a noun) and how they know (because it finishes in –ism.) And if you took away –ism? And so on. Once you’ve clarified that these are suffixes and they change the word type, ask them if they think the word is positive or negative. Go on to elicit which prefixes we have here and how they change the meaning of the word. Then get them to google the word for homework and be ready to teach some English history in your next lesson.