The clarity with which teachers convey the curriculum to students has significant implications for student learning. Students were asked about aspects of teachers’ mathematics instruction during their mathematics lessons: whether they know what their teacher expects them to do, and whether their teacher is easy to understand, has clear answers to their questions, is good at explaining mathematics, does a variety of things to help the students learn, links new lessons to previous knowledge (eighth grade only), and explains a topic again when the students do not understand. Responses were combined into the TIMSS Instructional Clarity in Mathematics Lessons scale, as described in Exhibit 12.8 (see About the Scale). Exhibits 12.9 and 12.10 present students’ reports about the clarity of their mathematics lessons, for fourth grade and eighth grade, respectively. Countries are ordered by percentage reporting “high clarity of instruction.”

On average, about three-quarters (74%) of fourth grade students reported that their mathematics instruction had “high clarity,” 21 percent reported “moderate clarity,” and just 5 percent characterized their instruction as having “low clarity.” There was a range in views across countries with, interestingly, lower percentages of students characterizing their instruction as having “high clarity” in some of the higher performing countries, such as Korea and Japan. On average, internationally and within most countries, however, more clarity was associated with higher average achievement. Across countries, average achievement was 508 among students reporting that their instruction had “high clarity,” 488 among students reporting “moderate clarity,” and 466 among students reporting “low clarity,” a remarkable 42-point difference between “high clarity” and “low clarity.”

Eighth grade students were less positive about the clarity of their mathematics instruction, with less than half (46%) internationally reporting that their instruction had “high clarity,” 41 percent reporting “moderate clarity,” and 13 percent reporting “low clarity.” As in fourth grade, some of the higher performing countries had the lowest percentages of students reporting that their instruction had “high clarity,” including Korea, Japan, and Hong Kong SAR. Also as seen in fourth grade, clarity of instruction was positively associated with achievement. On average, students reporting “high clarity” of instruction had an average score of 504, followed by an average of 482 for “moderate clarity,” and 467 for those reporting “low clarity.”