Jessyca Mayriam Oematan Pengarang SELFIANA P MBADI Dosen Pembimbing 2 Alexander Home Kabelen Dosen Pembimbing 1 Alexander Home Kabelen Penguji 1 SELFIANA P MBADI Penguji 2 Soleman Dapa Taka Ketua Penguji

This study is entitled: "The Effectiveness of Kahoot games in Improving vocabulary of the 11th grade science two students of SMAN 1 Kupang Barat the academic year in 2021/2022” This study aims to determine the effectiveness of Kahoot games on students' vocabulary knowledge and to see student development before and after learning to use Kahoot games. This research lasted for one week at SMA Negeri 1 Kupang Barat. The researcher chose class 11 IPA 2 students as the subjects of this research. This research is an experimental design with a quantitative approach. There were 201 students in grade 11, and the researcher took 30 students of 11th grade science two as a sample (10%) which is distributed into two groups, they are Control group and Experimental group. The researcher used three techniques to collect data: Pre-test, Treatment, and Post-test. In the pre-test, the researcher gave 40 questions consist of 30 multiple choice and 10 essays to measure students' basic vocabulary knowledge. In the treatment, the researcher used the Kahoot game to learn vocabulary. After the treatment, the researcher conducted a Post-test to measure and determine the progress and level of students' vocabulary mastery after learning by using the Kahoot game. From the results of this study, the researchers found a significant increase in students' vocabulary knowledge after treatment using the Kahoot game. The average student score has increased from 46.6 to 80,83. The presentation of the increase shows an increase of 80%. From these result, the researcher concluded that using the Kahoot game in the learning process was effective in increasing the level of students' vocabulary mastery. Thus, the Kahoot game can be used by teachers as a medium for learning English at school to increase students' vocabulary. Keywords : Kahoot, Games, Vocabulary, Using, Effectiveness