Abstrak
Vocabulary is a crucial thing to learn in language learning. This research objective was to find out whether there was any significant difference in students vocabulary achievement before and after using picture series at seventh grade SMPN 11 Tarakan. This research was an experimental research and used pre experimental one group pretest-posttest design. The population in this research was all of the seventh grade students at SMPN 11 Tarakan. The number of the sample in this research was 32 students. The sample was chosen by using purposive sampling technique. Class for treatment was VII-1. It consisted of 32 students. In analyzing the data the researcher was use paired sample t-test in SPSS 22.0. The research result showed that there was different mean score between pretest and posttest. It was proven by the result of the students’ mean score from pretest was 59.47 and 76.41 in the posttest. It means that the improvement of the students’ mean was 16.93. It showed that the improvement of the students mean score in the posttest was higher than pretest. The result of paired sample (2 tailed) 0.000 is lower than 0.05, it means that the picture series can give any contribution to the students’ vocabulary achievement. It can be concluded that using picture series is effective in teaching vocabulary.