My character just completed one year of college (he's taking extra classes and going in the summer so he can graduate in 3 years). The chapter I'm writing starts the same way as all the other chapters (because an interaction between him and one of his teachers is important), but then I switch to telling. I whiz through the next 2 years of college.
Why would I waste the reader's time showing those two years? Nothing important to the plot occurs. So I whiz through 2 years by telling the reader they passed. A little more than "Two years later," but basically telling.
See, Show don't Tell doesn't mean never tell. There's also Tell don't Show.