Writing skill is a skill that is considered difficult to be mastered for Junior High School students whereas writing skill and scientific thinking are very important in daily live. The aims of this research are finding three problems. First, it is to find out the differences of students ability in writing text of students’ observation result which used cooperative learning types such as; Students Team Achievement Division, Group investigation and Cooperative Integrated Reading and Composition. Second, it is to find out the differences of students ability in writing text of students’ observation result between high motivated students and low motivated students. Third,it is to find out the interaction between cooperative learning types; Students Team Achievement Division, Group investigation and Cooperative Integrated Reading and Composition with students motivation toward the writing ability of observation result text. This research was an experimental research. It used 3x2 factorial design. The population of this research was students grade VII at SMP/ MTs Muhammadiyah Purwokerto in academic year 2014/2015. The sample of this research was students grade VII from two schools/ madrasahs in Purwokerto. There were 40 samples for each model which used random sampling technique. The data collection was done by test and questionnaire. The data analyze used two ways ANAVA.
Research result showed that the mean of group was taught using STAD was 78.82, CIRC 65.89 and GI 60.61. The mean of students writing ability who had high motivation were 78.86 and who had low motivation were 58.04. the result of this research can be summarized that: (1) The ability to write observation result text for students who were taught using STAD was better than students who were taught using CIRC and GI. (2) The ability in writing observation result text for high motivated students was better than low motivated students. (3) There was an interaction between learning model and students motivation in writing observation result text.
Key words: cooperativelearning, writing, learning motivation