We foreign or second language teachers need to learn the vocabulary of that language, if we’re non-native.
We need the words to communicate in that tongue, English in my case and my students’. Also in order to teach it.
What can we do? For example reading a text with new vocabulary, from the Web, from novels, etc. The fact of looking up a word in the dictionary or using an online dictionary like Wordreference and thinking of that word makes you learn English vocabulary. An action like that – looking up the word – makes you learn the word. And if you see that word again, later on, it will ring a bell to you and it will be easier to retain and learn.
You’ll be learning a rather vast lexis! With practice and continuity, of course. That’s an example of a learning strategy, you may have others. Over time you’ll find you’ve learned a vast lexis, and you’ll be able to teach an ample vocab to your students too. The teacher can give what he has, and not what he doesn’t. If he knows many words his students more likely will learn many words too. / Photo from: WallpaperCave. The picture is just a nice illustration.