This paper reports a test on the feasibility and educational value of probeware and associated instructional materials in middle school science education. We addressed feasibility through consideration of costs, teacher professional development, and instructional design. In order to test our approach, we developed 2 middle school science curriculum units, 6 low-cost probes that interface between handheld Palm computers, and CCLabBook software for the Palms that presents the curriculum, interfaces with the probes for data collection and visualization, and supports guided exploration. The materials were tested by 30 teachers in the first year, and in a follow-up study by 8 of those teachers the second year. We found that teachers were able to conduct the investigations successfully in their classrooms, and that student learning was enhanced through the use of the probes and handhelds. Specifically, students experienced the physical correlation between phenomenon and modeling, which helped them to develop understanding and to confront misconceptions.