Thanks for asking. As you know, mentor texts can be incredibly powerful tools to help students see the beauty in our language—and studying mentor texts at the sentence level can help students see what happens when we craft together the best words in the best order.
I almost always use mentor texts to teach craft at the sentence level. We start each day with a notebook prompt, and I often use brief excerpts from essays or novels that illustrate thoughtful sentence crafting.
When I use mentor texts to teach at the sentence level, I focus three different elements: diction, syntax, and punctuation.