Global Research in Higher Education ISSN 2576-196X (Print) ISSN 2576-1951 (Online) Vol. 1, No. 1, 2018 www.scholink.org/ojs/index.php/grhe 98 Original Paper Using Project Based Learning (PBL) Design to Expand Mathematics Students’ Understanding: A Case Study in Statistics Problem Sugi Hartono 1* 1 Mathematics Department, Universitas Negeri Surabaya, Surabaya, Indonesia * Sugi Hartono, Mathematics Department, Universitas Negeri Surabaya, Surabaya, Indonesia Received: May 10, 2018 Accepted: May 20, 2018 Online Published: May 24, 2018 doi:10.22158/grhe.v1n1p98 URL: http://dx.doi.org/10.22158/grhe.v1n1p98 Abstract This paper describes some activities that the author has designed using Project Based Learning (PBL) to develop students’ understanding of statistics. This study used a quasi-experimental method with a one group pretest-posttest quantitative research design. The subjects in this study are 30 students of class VII in SMP Negeri 6, Surabaya, Indonesia. The data collected using a questionnaire and a test. The validity of students’ response used product-moment correlations and the reliability test used the Cronbach’s Alpha formula, and the hypothesis was tested using the t-test (one sample t-test). The results showed that the positive response of students using PBL design to expand mathematics students’ understanding of statistics, namely 85.83%. Furthermore, there was a difference in the students’ learning outcomes before and after they learned through the PBL learning design, indicated by pretest the mean of score is 38.30 and a posttest mean score is 67.17. Besides that, t observed of pretest is 15.931 and t observed of posttest is 34.655, both are greater than t table with a significant level α=0.05 is 2.042. Thus, we could be concludes that there as a difference the understanding of statistics students’ outcome before and after learning with PBL design. Keywords project based learning, mathematics students’ understanding, statistics 1. Introduction Classroom learning should be an effort for students to be able to develop material revelation, increase knowledge, and knowledge will be used later for future life. But in fact, lately a lot of learning is more likely to be boring and less interesting, especially in junior high, Surabaya so that many students are