The case method is a way that grown-ups learn stuff by pretending they're in a storybook. The teacher makes a make-believe world where there's a problem that needs fixing or a situation that needs improving. Then, the grown-ups pretend they're characters in the storybook and try to solve the problem or fix the situation by talking together and being creative.
Basically, it's like playing a really fun game where you get to be a detective or superhero and use your brain to solve problems. But instead of playing with toys, you use your grown-up brain and talk with other grown-ups who are also playing the game.
The case method is really helpful because it teaches grown-ups how to think critically and work together to figure out solutions to complex problems. Plus, it's way more fun than just sitting and listening to a boring lecture!