This course is for grade 3-12 teachers of science who want to understand and use item cluster design principles for WCAS (Washington Comprehensive Assessment of Science), and also want to gain experience using WCAS-style items and item clusters in various ways with students in the classroom (formatively and summatively). Teachers will work together online in small job-alike teams to analyze, modify, and design items, and will use Zoom to discuss students’ classroom experiences with WCAS-style items.  Many tools and resources will support participants in working with these assessments, including multiple examples of item clusters and several tools for incorporating the three dimensions of NGSS into WCAS-style assessment items.  As the course progresses, teachers will continue to refine one item cluster related to climate science.