Competency-based curriculum emphasizes giving direct experience. One form of activity that is often carried out by junior high school science teachers in learning is observation and practice by using Student Worksheets (LKPD). But in fact the LKPD used as a learning resource so far seems boring and difficult to understand by students. Based on these problems, this study aims to develop Problem-Based Student Worksheets (LKPD) on Valid, Practical, and Effective Water Animal Classification Material. The development procedure uses a 4-D model which includes defining, planning, developing and distributing. The study was conducted on VII grade students of SMPN 4 Rambang Dangku in Odd Semester 2018/2019. The instruments of data collection were used in the form of questionnaires, interviews, initial test questions, and final test questions. Data analysis techniques using Microsoft Excel 2010 applications. The results showed that: 1) the results of expert lecturer validation were 77.7%, 91.6%, 77.9%, and 91.4% with very valid qualifications; 2) the results of the development trials show an average score of 81.7 with excellent practicality qualifications; and 3) the results of N-gain analysis validity test with an average value of 0.68, meaning that problem-based LKPD is quite effective in improving student learning outcomes.