WebQuests are designed to ensure meaningful learning by combining technology with a constructivist approach in the classroom setting. This study aims to examine the effect of WebQuests used in instruction on students' academic achievements and the student and teacher opinions on WebQuests. The participants of this study using the quasi-experimental method were composed of 78 ninth-grade students and five mathematics teachers. Within this scope, WebQuests for the attainments in the domains of Data, Counting and Probability learning in the ninth-grade curriculum were developed by the researchers. The academic achievement test developed by the researchers was applied to the experimental and control groups as pretest, posttest and delayed posttest. In the implementation process, the experimental group was expected to solve the non-routine problems within WebQuests. The student and teacher opinions on the implementation were received at the end. The SPSS software package was utilized for quantitative data analysis and the qualitative data were subjected to a content analysis in the study. Consequently, it was discovered that the WebQuest teaching strategy had a positive impact on the student learning retention. Furthermore, the themes obtained through teacher and student opinions and recommendations of the study emphasize important issues for future studies.