The objectives of the research are: (1) to examine the teacher’s strategies to assess students’  writing  by  using  Think-Aloud  Protocol (TAP),  (2)  to  investigate the  students’ practices in TAP process, and (3) to investigate the teacher’s instructional strategies based on TAP Assessment.
The method that is used in this research is the descriptive qualitative method. The
research was conducted in August 2020 at a high school in Magetan. The population is the written products of ninth grade students of a high school in Magetan. The class consists of 28 students. The writer used their written products as the population. By applying purposive sampling,  the  writer  used  some  samples  as  the  representatives.  Fifteen  students  are interviewed and ten students’ written products are analyzed. The instruments to gather the data are in the form of document analysis, interview, and questionnaire. In this research, the researcher applied triangulation to check the validity of data.
The results of the study show that (1) in assessing the students’ writing by using TAP
the teacher notes down students’ mistakes, confirms by asking students to reread their written products, instructs the students to record their voice, and assesses the students’ revised written products; (2) during TAP process the students talk aloud mostly in Indonesian and Javane se, take pauses to combine ideas and to revise mistakes, and reread their written products before submitting them; (3) the teacher discusses, explains, and gives examples in the online class and asks the students to rewrite their written products.
The findings in this study can be used to explore the teacher’s strategies in implementing TAP assessment  and his instructional strategies based on TAP assessment. They can also be used to explore the students’ practices during TAP process.

Keywords: Assessment, Feedback, High School, Think-Aloud Protocol, Writing