The importance of vocabulary in the English language cannot be overstated. A sufficient vocabulary is required to construct a sentence. As a result, the researcher used an approach in the classroom to stimulate students to learn language. The purpose of this study is to improve the vocabulary mastery of the seventh-grade students at SMPN 1 Mojo Kediri in the academic year 2021/2022 by using crossword puzzles. The design of the research is Classroom Action Research (CAR) and was conducted in one cycle that consisted of four steps: planning, implementing, observing, and reflecting. The research was conducted at SMPN 1 Mojo Kediri that consist of 30 students. The data was collected by using test. These data was analysed using percentage of the total of students’ who can pass the test to see the improvement of preliminary test and cycle test and to get a conclusion as the result of this research. Researchers made an agreement that the student achievement increased if they earned a score of at least 75and the average score is at least 75. The results show that there is an improvement of students vocaulary mastery. There are 27 students (90%) from Preliminary tests which are still below the score of 75, and only 3 students (10%) who receive at least 75. Meanwhile, in cycle tests 1 there are 24 students (80%) which score above 75, and 6 students (20%) that scores below 75. Continued with cycle test 2 and a result of 30 students (100%) managed to score above 75 all. Thus, the use of crossword puzzle to improve the vocabulary mastery of seven grade at SMPN 1 Mojo Kediri the result was very significant.

Pratiwi , Desti .   (2022). Improving students’ Vocabulary Mastery by using Crossword Puzzle at SMPN 1 Mojo Kediri. IAIN Kediri