Currently, primary and secondary school education quality is a major source of concern for educators. A significant number of factors, such as the development of scientific and technological progress, technological innovations, and digitalization, affect the quality of education. In recent years, teachers have come to believe that the textbook they choose has a big influence on their students' academic performance. To determine the difficulties of selecting e-learning materials for primary school students, a quasi-experimental study was conducted. The challenge of choosing instructional materials was examined using the example of a teacher's selection of a mathematics textbook. The purpose of the study was to determine the extent to which the teacher's selection of an e-textbook for mathematics instruction affected the performance of fourth-grade students. The two selected test groups of the same size (140 students) included students from an elementary city school in Russia. The participants were nine years old on average. Participants in the second experimental group performed better on the final test (74.71) than those in the first (65.9), per ANCOVA analysis. There was a significant difference between the two groups' test results (F = 10.84, p < 0.05). The findings demonstrated that primary school students' performance levels can be significantly impacted by the choice of electronic textbooks to teach them. Additionally, the study indicated useful criteria for the selection of high-quality e-textbooks by teachers. These criteria allow educators to make a choice that may significantly influence the educational process. The findings of this study demonstrate that using e-textbook approval guidelines based on theoretically sound quality indicators can help prevent the use of subpar textbooks in classrooms and raise the standard of textbooks in general. The educational opportunities offered by primary school textbooks may also have an impact on students' performances in higher grades.