How to lecture without saying a word

There are so many things that we want to tell our kids, but when they become teenagers, or precocious 9-year-olds, they no longer want to be told what to do. My efficient way to lecture is to let other adults do the talking. When we flew when the kids were young, if I wanted them to stop kicking the seat in front of mine, I'd ask the airline hostess, or the passenger to look sternly at my kids and tell them to knock it off. It terrified them, and they stopped. Now that one of my daughters is a teen, rather than explain to her about the dangers of bullying or sexting, I just find articles in newspapers, magazines, and leave them on the breakfast table, and I don't say a word. She usually picks them up, reads them through, and then she initiates the conversation on the topic. Voila! I don't preach, but the message gets through anyway.