This thesis aims (1) to identify the improvement of students’ readiness when WhatsApp Messenger is implemented; and (2) to identify problems which may occur in using WhatsApp Messenger to improve students’ readiness.

The method used in this research is a classroom action research. The research was conducted from 14th January until 14th April 2016 at XI MIPA 8 of SMA Negeri 3 Surakarta. The research was conducted in two cycles, in which 6 meetings were conducted in each cycle, 3 meetings for WhatsApp Meeting and 3 meetings for Class Meeting. Every cycle consists of four steps: planning, implementing, observation, and reflecting. The research data were collected using questionnaire, observation, tests, and diary. The data were analyzed through assembling data, coding the data, comparing data, building interpretation, and reporting outcomes for the qualitative data and descriptive statistics for the quantitative data.

The research findings showed that the improvement of students’ readiness in each meeting had improved when WhatsApp Messenger was applied. The improvement of students’ readiness included ability to (1) follow structured daily routines; (2) work independently; (3) listen and pay attention to others; (4) cooperate with others; and (5) follow simple rules. However, there are technical and educational problems dealing with the use of WhatsApp Messenger to enhance students’ readiness. To solve the problems occurred in each WA meeting, there were discussions between the teacher and the students in the end of the class meeting.

Based on the findings as presented above, WhatsApp Messenger is an alternative to make the students ready for school. It also becomes a multi-function media which can improve students and teacher relationship.

Keywords: WhatsApp Messenger, students’ readiness, action research