First, the 9/11 one was more subtle. Instead of Arthur's dad being at ground zero or a plane crashing at the library, it's a simple school fire. This allows people to make their own connections while keeping it grounded and making it easier to relate with.
Second, they didn't outright look at the camera and lecture people about it. INB4, video call is just a paper thin excuse.
Those are the two off the top of my head. If they wanted it to make it like the 9/11 episode, they could have made it where a school bully is really digging into one of the kids for some reason. The adults don't do anything because they don't properly understand the situation. Eventually, the bully goes too far and the kids come together to all go to the principal and give him no choice. This is just an off-the-top-of-my-head way they could've done it.