...sharing thoughtful, mentor text-inspired lessons your students will love!
I've been using the ACES constructed response from the Nevada Writing Fix web page. I do teach 4th grade, however, a few 3rd grade teachers grasped onto the format and used it with their students as well. It's a great tool to get them going...
Also - Wiki-Teacher has some lessons for constructed responses as well.
I'm not sure if you've hit these already, so just in case.
What math series do you use? We use Everyday Math, and it has some great writing prompts built into each lesson.