Although some of the lesson plans are relatively vague, this a pretty solid site overall. There are a number of lesson plans here that could be adapted to fit your specific unit/essential questions.
The best thing about these lessons is that the lesson documents (PDFs) contain a wide variety of primary and secondary sources that you can use in a variety of ways.
The Zinn Education Project is free to sign up for and use.
This framework helps was created to help drive instructional practice. Specifically, collaborative group work, writing to learn, literacy groups, questioning, scaffolding, and classroom talk.
Kagan Structures are instructional strategies designed to promote cooperation and communication in the classroom, boost students' confidence and retain their interest in classroom interaction. The Structures work in all teaching contexts-regardless of subject, age group, and number of students in class.