To understand how the picture series works, students need to look at it abstractly. Similarly, when they express ideas to build a solid stories  based on the pictures, they must think about it abstractly too. Both of these will be easier to do if the teacher can use the picture series. The picture series not only can help students to get realistic ideas in understanding descriptive texts but also in building ideas to make them.
In line with the explanation above, picture series is a good learning medium for the activity of writing descriptive texts. The use of picture series in learning can make students learn more easily and teachers teach easily which is the main part of the learning process.
The picture series is not only an interesting learning media for students, but also the right media that can make it easier for students to develop ideas through the pictures they see. This will be good for students in the process of learning to write descriptive texts.
RESEARCH METHODOLOGY
Â
Research Design
This research deals with the design of Quasi-experimental research to investigate whether the use of picture series as a teaching media can improve students' descriptive text writing skills or not.
Quasi experimental based on Ary et al (2010:316) Quasi-experimental designs is a research design  that involve manipulation of an independent variable but differ in that subjects are not randomly assigned to treatment groups. While, White and Sabarwal (2014:1) stated:
"Quasi-experimental designs identify a comparison group that is as similar as possible to the treatment group in terms of baseline (pre-intervention) characteristics. The comparison group captures what would have been the outcomes if the programme/policy had not been implemented (i.e., the counterfactual). Hence, the programme or policy can be said to have caused any difference in outcomes between the treatment and comparison groups."
The Quasi-experimental design focuses on treatment and results, therefore data is taken from the pre-test and post-test to find out whether the picture series as teaching media is significantly more effective than conventional methods in improving students' descriptive text writing skills.
In this research design, there are two classes used. One class is an experimental class which is treated with picture series in improving students' descriptive text writing skills. Another class is the control class which got the conventional method. The quasi-experimental design formula based on Ary et al (2010: 316) is explained as follows:
