Wniting is most likely to encourage thinking and learning when students view writing as a process. In teaching leaming process a language , there are five aspect that support four language ability above such as: grammar, vocabulary, mechanic, form and generic structure that are also taught in English teaching and leaming process. The objectives of this research are (1) to describe the writing ability of hortatory exposition on control class at second year students of SMAN 4 Kediri, (2) to describe the writing ability of hortatory exposition on experimental class at second year students of SMAN 4 Kediri, (3) to find to know whether there is significant different between students’ writing ability of hortatory exposition on experimental class and control class at second year students of SMAN 4 Kediri, (4) to know whether teaching writing by using think pair share at second year students of SMAN 4 Kediri is effective or not. The research design used quantitative experimental design and the methods are control class and experimental class design. The subject of this research is second year students of SMAN 4 Kediri that are the sample were IPS IV as the control class which consist of 27 students,and IPS VI class which consist of 27 students. to get the data, this research used test, they are test for control class and test for experimental class. After getting result of score between control class and experimental class, the data was couted by using SPSS to find t — test. It is used to find out whether there is significant difference result between control class and experimental class. In this research used formula as follow:
to : M1 - M2
SE M1-M2
Besad on the result of research, The result of statistical computation values of the test is 2.725 while t-table with degree of freedom (df) 75 at 1% significant level is 2.64. It can be seen that t-statistic value is higher t-table. Because there is a significant increased in student’s writing after being taught by control class and experimental class strategy, it can be concluded that there is significance difference between the students’ ability in writing which are taught by using student teams ability division and taught by using think pair share strategy. So, the alternative hypothesis was accepted. It is recommended of research was: (1) the students’ writing ability in hortatory exposition for control class without using think pair share is fair category. (2) the students’ writing ability in hortatory exposition for experimental class by using think pair share is a good category. (3) There was significant difference between the students’ writing ability hortatory exposition in experimental class by using think pair share and control class without using think pair share so it can make easier to the students understanding and mastered the writing ability.

Key words: Writing, Teaching Hortatory Exposition, Think Pair Share Strategy.