"Show don't tell" is one of those writing maxims that gets thrown around with little explanation. Scribophile Academy has a good article on it here. It's true that "telling" the entire way through your story is uninteresting and doesn't immerse the reader in your story. On the flip-side, "showing" every. single. thing. is very time consuming and not always that effective - especially if you've got a limited word count to work in.
Back in primary school, I learnt this about narrative writing: There's an orientation (setting the scene), a complication and a resolution (where the complication is solved). Sound familiar?
Then, in high school, I learnt the same thing, before moving on to maxims like "show, don't tell" (more on that later) and techniques like dialogue and metaphor. I learnt how to write good sentences, maybe even good paragraphs.
The thing that was missing - and it's an absolutely crucial thing - was how to create a plot. We moved straight from structure to technique, without much consideration of content. Students are learning how to write a story, sure. Are they learning how to write an interesting story?