Abstraks - The internship program implemented by the school LPTK young teacher often confronted with obstacles. Mastery of materials, inability to classroom management, and weak in manufacturing media learning resources. Factors that make young teacher internship process is not optimal. The quality of teaching and teacher competence praktikan can be enhanced through the lesson study. How efforts to improve the quality of learning by teachers praktikan during teaching practice through Lesson study? Lesson study is a model of coaching (training) educator profession through assessments and ongoing collaborative learning based on the principles of collegiality and mutual learning to build a learning community. Subjects in this study were two female students of biology education courses PGRI Semarang State University as a teacher practitioner. The study was conducted at SMAN 2 Mranggen in class XI-2 and XI MIA MIA-3. The data in this study include doing  lesson study, the ability to manage the classroom, teacher competence and achievement of learning outcomes biology students. This research was conducted during the 8 cycle (plan, do and see) with the details of as many as four cycles in class XI MIA-2 and as many as four cycles in class XI MIA-3. The results showed that the average observed the implementation of learning practices that reach grade 81 teachers praktikan 1 and 83 for teachers praktikan 2 . The result of study biology students has increased 20% from the initial value of both class XI-2 and XI MIA MIA-3. Similarly, the classical completeness increased 30% for class XI MIA-2 and 32% for class XI MIA-3. Lesson study activities can help students to improve academic skills and participation of students in each learning activity. Lesson study activities can improve the quality of teacher learning practitioner who is teaching practice and help resolve difficulties in the learning process in the classroom.