Developing group theory textbook which connected to the school mathematics' contents

As part of abstract algebra, the group theory is considered as a difficult subject for pre-service mathematics teachers (PMTs) since it seems not related to the future teaching. In line with the Klein's double discontinuity that the learning of group theory at the university did not bring the content from school mathematics and in the school level mathematics' content did not connected to the university mathematics. Therefore, the current study intends to develop the group theory textbook which connected to the school mathematics that provide the PMTs with the mathematical connection. The study involves the educational research and development cycle refers to Borg and Gall's model, which is adjusted to the need of this study. The research procedures consist of three main stages: collecting data, planning, and developing the product. There is a significant need for further studies to be done in this area to implement this group theory textbook to obtain how PMTs aware to the mathematical connection from school mathematics and vice versa. Furthermore, it is essential to conduct the study about the effectiveness of this textbook. Particularly, in overcoming the PMTs' difficulty in the learning process of group theory subject.