In this part of the lesson, the teacher gives a quick review of inscribed and central angles. The teachers gives directions for students to carry out the error analysis.  She instructs students to find out if their friend is correct and if not explain what they should have done to make the answer correct.  

As the students are working with a course-level problem, the teacher is circulating to guide students in their error analysis.  Students explain their thinking to their teacher and to other students. 

This clip shows how the teacher\'s questioning helps students as they struggle to write out the mathematics errors that their friend did incorrectly. The teacher helps students to finish the 1st question by summarizing a student response. 

In this part of the lesson, students talk about and ask questions about each other’s thinking, in order to clarify or improve their own mathematical understanding.  Student explanations of their scoring of error analysis helps other students decide when to give a a 4 or a 3.  The teacher incorporates these student conversations in her summary. 

After a brief transition to move into differentiated groups, the teacher gives specific directions about the group work.  All students have the opportunity to work with and practice course-level problems.  

 3A, 3D:  Students share their developing thinking about the content of the lesson.
The teacher encourages one student to be a \"spy\" and get help from another group.  Student conversations about solutions helps group members and also helps the visiting student.  Teacher listens to student conversations and only interjects when student understanding is incorrect.  The teacher guides the group to find an error earlier in the discussion.  Students persevere in finding the correct solution. \r

In this part of the lesson, the student comes back from visiting another group. The teacher questions this group to make sure students know relationships for central and inscribed angles.  Teacher guides the students in the right direction to correctly revise their work. 

The teacher helps students find the correct terminology and notation to describe their angles and explain the correct answer specifically.