Project-based learning offers the opportunity to apply theoretical and practical knowledge, and to develop the student's group working, and collaboration skills. In this paper we presented a design of effective computer class that implements the well-known and highly accepted project-based learning paradigm. A pre-test/post-test control group design investigation was undertaken with 98 students from 6th grade students (male and female) enrolled in computer class at the elementary school in Koprubasi, Trabzon, Turkey in the 2002-2003 academic year. Students were randomly divided into two treatment groups. One group (50 students) formed the control group. Other 48 students received the project based learning treatment. The effect of the project based learning on students' computer skill achievement level was assessed using the "Rubric," an instrument that was developed during the study. "Group and Self evaluation forms" were used to measure the learning outcomes related to the teamwork, communication and social skills. The results have been found to be positive and are discussed.