Here's an idea that Andrew Wright suggested in his recently session at IATEFL: to, first, get your learners to list everything they know about gardening; and, then as a discussion activity, to talk about how that could be related to life.
As I live and work in Barcelona, where virtually no one has a garden, I picked cycling for the example (image, above) that I created to show to the group I tried this with. And I let them pick literally any of their own interests.
I instructed them to list, among other things, the slightly bizarre, slightly nerdy, slightly tongue-in-cheek things about their hobby (my example was that the only really good thing about cycling is the amount of food you get to eat!). I also asked them to make all the items on their lists impersonal — achieved in part by pairing them as far as possible so that two people were creating the list on a hobby they shared.
Probably best as a task for adults rather than my teenagers (could you relate painting Warhammer figures to life 😉 ?).
My idea was to get them to use their phones, and the pictures I was hoping they would have there, to illustrate the whole thing. The Over app would have been brilliant for adding captions but we didn't in the end get there.
We used pen and paper to create the list, but list.ly is a great alternative if you want to do activities with lists.
See also my article on OneStopEnglish for 10 fun tasks with lists (subscription or 30-day free trial required).