THE INFLUENCE OF CRITICAL THINKIN DEVELOPMENT USING CHEMISTRY MODULE TO INCREASE STUDENTS’ ACHIEVEMENT IN BUFFER SOLUTION TOPIC GRADE XI RSBI SMA NEGERI 1 BERASTAGI YEAR 2011/2012

The influence of critical thinking development in learning Buffer Solution concept through chemistry module to increase students' achievement grade XI is explained in this thesis. The study is aimed to know the propriety level of chemistry module, knowing the effect of using the chemistry module that developing the critical thinking of students, and also to know the effect of the chemistry module to increase students‟ achievement. The population in this study are all students in RSBI SMA Negeri 1 Berastagi grade XI Science in Karo District. The sample of this study is two classes which is categorized as one experiment class and the other one as control class. The instruments are using multiple choice test to see the students' achievement and essay test to measure the critical thinking development. The instrument of research is standardized by used validity and reliability test. The propriety level of buffer solution module that developing the critical thinking of student is 97.5%. Based on data analysis obtained average value of initial test (pre-test) in experimental class is (23.28 ± 6.30), while in control class is (28.91 ± 5.642). While average value of post-test in experimental class is (86.25 ± 8.89), while in control class is (81.09 ± 6.688). The students‟ achievement from normalized gain which taught using critical thinking development through module is 83% whereas in control class(with common module) is 74%. The statistic analysis shows difference significant with tcount (3.75) > t table (1.6589). And the correlation between students' achievement and critical thinking average is r = 0.96. So, we concluded that the students' achievement which taught by using module that develop critical thinking is higher than students' achievement in control class, and there is a positive correlation between critical thinking skill with students‟ achievement (Gain).