I'm reading through Lucy Calkin's Units of Study and Unit 2 is talking about having the kids use "twin sentences." She gave an example, but it's just not computing in my head. How are these sentences twins? And how do I teach it more clearly to my kiddos? She mentions it in a mid-workshop interruption lesson. I want to teach it as a minilesson. I can't find anything helpful when I google it. I'm hoping you all can help.