I attended a workshop last summer at the Math and Science Innovation Center in Richmond, Virginia. I was able to sit through a session where a 3rd grade teacher had created design briefs based on the Social Studies and Science Curriculum we're required to teach. Basically I had been overthinking this whole process and the light bulb finally went off.
I created 8 Design Briefs last year and I've uploaded them on The Teaching Oasis. They're mainly for Social Studies as I haven't taught Science for 2 years. I do plan to create one for every single Science and Social Studies standard for the Virginia Curriculum.