Prepositions

So the other day we started with the advanced students and I taught a lesson on prepositions (in, on, around, above...) using a recipe. Well, the lesson was great, as I planned, and everything went well, but as advanced students I assumed they would have more vocabulary, especially kitchen/food vocab. which seemed pretty basic to me, but they were lacking quite a bit. This led to the cutest mistake ever. One guy in my class is Uriel, and he's about 23, very good at English and studying biochemistry or something. Anyway we were talking about vegetables in the supermarket and I mentioned a salad, and using lettuce. He didn't know what it was, so I drew a picture, and thinking I would throw in a challenge, said "Lettuce is leafy." I pointed to the leaves of lettuce and the other , Solange, and Uriel both nodded as if they got it. So I said Uriel, can you use leafy in a sentence? And he says "Yes. I will put lots of leafies of lettuce in my salad." How cute is that??? SO then I had to explain that leafy is an adjective bla bla bla, but it was hilarious and we all got a giggle out of that after he was gone. And of course we all now make our salads with leafies of lettuce.