So I mostly taught myself photography basics at ages 14-15 via posting and receiving help on old forums known as
phototakers.com or something lame and a skate photography website called
wheelsandwax.com where actual pro photogs would hang and give Crit. A few things that really helped me:
1) Seeing images I liked and asking the poster questions about how they shot it.
Bring some of your favourite photos, maybe 5-6 that are all quite diverse. Show them with the intent of them generating questions, so don't just simply pick your 'best shots' or whatever. Have a Q+A session and pair it with #2
2) Being able to fiddle with a digital camera and see how adjusting settings affects the image live on the rear screen. While answering questions about how a photo was done, have everyone literally mimic the settings while you explain why they are the way they are and try to use / find a similar light condition at the same time (IE a backlit photo with a silhouette subject or whatever). You can pull in exposure triangle stuff into these answers.
DO NOT just explain exposure triangle without lots of visuals AND the kids fiddling with their cameras while you explain. Exposure triangle makes zero sense and is dry/abstract as fuck without the kids being able to manipulate their cameras simultaneously.
3.) Receiving productive criticism on photos. Not sure if you'll be able to do this...but man people with no photography experience just lack even the most basic instincts that typically are good rules to follow (like making sure the horizon is straight).
Anyway, the less talking you do and the more they get to physically use their cameras and visually see how to manipulate the look of their images the better. Kids are stupid and smart at the same time, so don't underestimate them but don't bore them with charts and long verbal explanations.
Pic related: some photo I took when I was 15 after finally starting to get a feel for using off camera flashes.
