This research is aimed to reveal whether: (1) PALS is more effective than Scaffolded Writing Strategy to teach writing; (2) The students with high critical thinking have better writing skill than those having low critical thinking; and (3) There is an interaction between teaching strategies and students’ critical thinking.

This experimental research was conducted at the eleventh grade of SMA Kartikatama Metro  in the academic year of 2015/2016. From four classes, the researcher took two classes as the sample, namely experimental class which was taught by using PALS and control class which was taught by using Scaffolded Writing Strategy. To find out the sample, a cluster random sampling was implemented. Each class was divided into two groups of which each consisted of students who have high critical thinking and those who have low critical thinking. To gain the data, two instruments were used. Those were writing test to find out the score of students’ writing skill and critical thinking test to find out the score of students’ critical thinking. The data were, then, analyzed by using Multifactor Analysis of Variance ANOVA 2x2 and Tukey Test. Before conducting the ANOVA test, pre-requisite test such normality and homogeneity test were conducted.

There are some research findings which can be taken: (1) PALS is more effective than Scaffolded Writing Strategy to teach writing; (2) The students with high critical thinking have better writing skill than those having low critical thinking; and (3) There is an interaction between teaching strategies and students’ critical thinking in teaching writing.

Based on the results of this research, it implies that PALS is an effective to teach writing to the eleventh grade of SMA Kartikatama Metro. However, to support the using of PALS, a teacher is recommended to combine the strategy with an interesting teaching materials and teaching media. It will make the atmosphere of the classroom more interesting so the teaching learning process can be more effective.

Keywords: PALS, Scaffolded Writing Strategy, writing skill, critical thinking, experimental study