Hypotheses REVIEW TO THE RELATED STUDY
61
through experimentation, cause and effect relationship can be identified. The purpose of experimental study is to investigate the cause and effect
of a certain condition.
Considering the explanation above, related to this study, the
writer used an experimental study because the aim of this study is
revealing the effect of teaching materials and learning motivation towards students‟ writing skill. It involves three kinds of variables.
The first variable is independent variable. In this study, the independent variable is teaching materials. It is also recognized as an
experimental or treatment variable. They are two teaching materials that are used in this study, namely computer based communication teaching
and textbook teaching. Both of these materials are used differently for groups of students at the first semester of Grade XI of SMAN 5
Yogyakarta in the academic year of 20152016. Fraenkel and Wallen 1993: 242 also explain that in the experimental research, it is
important to make comparison group because it serves the purpose of determining whether the treatment has had an effect or whether one
treatment is more effective than another. In this study, the group that received computer based communication is the experimental group and
the group that received textbook material is the control group. The second variable is a dependent variable. The dependent
variable in this study is writing skill of the students at the first semester of Grade XI of SMAN 5 Yogyakarta as the advanced level students. In
62
short, considering the explanation above, this experimental study used two groups, namely experimental group and control group.
The third variable is a secondary independent variable. It is selected to determine if it affects the relationship between the primary
independent variable
teaching materials:
computer based
communication and textbook and motivation. In this study, learning motivation as the last variable that was labeled with two different
names, i.e high learning motivation and low learning motivation.