Explaining things that matter:
Be simple. Then simpler than that.
Just say what happens.
The part of reality that any given person needs to know is naturally riveting to them.
Franklin Delano Roosevelt's Secretary of Labor was Frances Perkins, the first secretary of labor in the new department, and the first woman cabinet member. She knew how Roosevelt like things explained--simple, short.
One time she arranged for an activist with an idea of what should happen to have a short time with Roosevelt. This guy was into impressing Roosevelt with his smarts. He didn't.
After he left, (his time was not extended), Roosevelt asked Perkins what the man was trying to say. Perkins told him. Roosevelt said, "Well, why didn't he say that?!"
Roosevelt got a lot done with radio fireside chats, where he explained what was up and what he wanted to do about it to people in general. One reason he did his output that way is that is how he liked his input.
"The Roosevelt I Knew" by Frances Perkins is a great read about how things can happen in government. It makes it clear for example that Frances Perkins and Eleanor Roosevelt didn't really hit it off as people. but that they were both aware they were very important parts of the liberal branch of the Roosevelt administration, so they found ways to act toward the same ends without hanging out much together.
Perkins gives the feeling that if Eleanor had run a little faster, gotten there just a little bit sooner on the issue, the Japanese would not have been interred. Presumably she would have said something common sense and humanizing. But the security guys got there first.
Perkins came from being an activist in New York City and then a member of New York State Government. When the Triangle shirt factory fire happened and many young women were burned alive, she told the story of factory conditions in general as simply as she could. She took legislators on tours of facories so they could see, feel, smell the conditions.
At the time of that fire and Perkins' teachable moments follow-up, Franklin Roosevelt was in Washington, D.C. being assistant Secretary of the Navy. Perkins had a lifelong regret that he hadn't been there to be taken on those tours, because she thought he would have been better and more active on labor issues if he had.
However, liberal he looks from here, she thought he could've been more, with simple education.