This paper reports on a research study examining the benefits of investigations as non-traditional assessment tasks in the lower secondary school. A mathematical investigation is defined as an inquiry into a mathematical situation, the topic of which may arise from real life or a mathematically designed problem. Students are required to apply familiar skills and concepts to the unfamiliar situation of the investigation. In this study, the investigations used were assessment items that were part of the normal school program. Four teachers and 18 students participated in the study. The main methods of data collection were interviews and observations. Both teachers and students participated in the interviews. The observations, however, were more focused on the students. Student journal writing, related documents and artifacts, and student samples supplemented this data. The major findings from the study were that the investigations enabled students to learn more effectively, to become more involved in mathematics at school, and to interact more frequently with each other. Specific findings from the interviews revealed that students felt more challenged in mathematics and developed a greater understanding of the concepts involved. The observations were consistent with the interviews and showed students actively engaging themselves in the mathematical processes of the investigation. (Author/ASK)