The aim of this research was to examine the effects of mathematics activities prepared by using Jigsaw II technique on fourth grade students. A mixed design was used, consisting of a combination of pre-test post-test without control group a Quasi-experimental design and qualitative data. The research's study group consisted of 21 fourth-grade students. The researchers created math activities for the Jigsaw II technique which were used throughout the process. The "Mathematics Attitude Scale" and "Constructivist Learning Environment Scale" were used as pre-test and post-test data collection. In addition, at the end of the application, students' opinions on the application were recorded. The Wilcoxon Signed Ranks Test was used in the analysis of the data, and content analysis was used to analyze the student views on the application, as well as direct quotations from the students' statements. The analysis concluded that there was a significant difference between the pre-test and post-test average scores of the research group's mathematics attitude and constructivist learning environment situations of the in favor of the post-test. At the end of the process, most of the students expressed positive opinions about these activities. This technique is recommended to use more frequently in classrooms because it improves students' attitudes towards mathematics lesson and constructivist learning.