Well, for my oldest, it's a new universe in many ways. He's in 8th grade and knows several kids there from elementary school. He's in Athletics, which is a stretch for his 5'7", 115 lb self. Actual conversation I overheard yesterday between him and the 11 year-old girl.
Boy: Today we did the bench!
Girl: What's that?
Boy: Well, you lay down on it, and there's a bar, and you hold it in your hands and slowly let it down to your chest and then push it back up.
Boy: Well, you use it to build muscles. It weighs 45 pounds, and you can put weight on it if you want.
I just about fell over at that last comment, like the weights on the end of the bar are just optional.