The purpose of the present study has been to explore the effect on students of an alternative measurement and assessment tool developed for the science unit on "Matter and Heat." Inspired by the teaching technique of concept development and the alternative measurement tool of the descriptive branched tree, an alternative measurement tool of web design was developed to conduct experimental research with 62 students at a primary school in Samsun. Results showed that, compared to the control group students who were instructed with traditional teaching approaches, the experimental group students who were tested with the web-based measurement tool recorded a statistically significant difference in achievement in the unit on "Matter and Heat." No significant difference, however, was observed in these students' attitudes toward the science and technology lessons. It is believed that developing an alternative measurement tool of web design encompassing all of the units of the eh, 7th and 8th grade science and technology curriculum will be of benefit to students and will make an important contribution to the work of teachers.