APOS Model is a model of Mathematics Learning Based on APOS Theory, which is student-centered and has syntax with phases: Orientation, Practicum, Small Group Discussion, Class Discussion, Exercise and Evaluation. The Worksheet is designed to support the APOS model, which is contain activities for each phase. In the practicum phase, the Worksheet contains a command from one of the appropriate computer application programs. In the small group discussion phase, the Worksheet contains questions related to the results of the lab work and new questions that are solved manually by the students. In the class discussion phase, the Worksheet contains a command to present the results of the discussion. In the Worksheet training / evaluation phase the worksheet contains about the Calculus questions. The APOS model has been applied to integral calculus courses by students of class A mathematics study program S1 FKIP UNIB 2017/2018 TA. The aim of the article is to explain that the APOS Model can build critical, tenacious, and confident characters. Data was collected through: observations, open questionnaires, interviews, and results of the Midterm exam and Final Exam. The results show that there was a better change in character after several meetings especially after the Midterm exam. When it came to the integration technique chapter, the topic was difficult but many students were able to study it well. This is indicated by the value of the Final exam. The result which is included in the effective category. There are 5 selected students who are able to complete the Worksheet in Chapter Integral unnaturally, without the guidance of lecturers. It can be concluded that the APOS model can help building critical, tenacious, and confident characters.