How about making teenagers seek out independent media? We've seen the results of people being raised reading MSM newspapers and it's not pretty. Propaganda packaged as "serious news", is some of the most dangerous media that exists.
They taught the teenagers how to question and interrogate the claims presented in the newspapers, which is far more effective than blindly branding 'MSM newspapers' as propaganda. (The study was conducted in France; are you sure that conventional French newspapers are propaganda of any inclination?)