I have a few thoughts on that one. First, I‘d try and teach that changing one‘s opinion based on new information is good and admirable and that not knowing something or not having an opinion on something one doesn‘t understand is fine.
Specifically for media, something like this paper is excellent though obviously not child friendly, I think even way too little adults are aware of this sort of framing that media and companies regularly do:
So trying to show/explain, how does framing something differently change the perceptions of people?
Another important thing in my mind is teaching something like Plato‘s allegory of the cave, so how we are presented the world is how we see the world and nobody knows everything about it because we only see a small part of it. That ties back in with my point about it being good to question one‘s beliefs from time to time.