The science content domains and underlying topic areas assessed in TIMSS 2019 are documented in the TIMSS 2019 Science Framework, which was developed in collaboration with the participating countries. The science topics included in the TIMSS assessments do not represent the intersection of the topics that are universally taught but rather are a forward-looking conception of science teaching and learning.

Exhibit 13.4 (see About the Scale) shows the science content domains—life science, physical science, and Earth science—and the 26 underlying topics in the TIMSS fourth grade science assessment. There were 7 topics in life science, 12 in physical science, and 7 in Earth science. Exhibit 13.6 (see About the Scale) shows the same information for the eighth grade science assessment, with its four content domains—biology, chemistry, physics, and Earth science, and the 26 underlying topics. There were 7 topics in biology, 8 in chemistry, 7 in physics, and 4 in Earth science. Teachers were asked to indicate, for each topic, whether it had been “mostly taught before this year” to students in the assessed class or “mostly taught this year,” or had been “not taught or just introduced” to students. This information serves as an indicator of the “implemented curriculum.” It can be examined together with information provided by TIMSS National Research Coordinators about whether each of the TIMSS 2019 science topics was included in their countries’ intended curriculum through the fourth or eighth grade and, if so, whether the topics were intended to be taught to “all or almost all students” or “only the more able students.” This information about the intended curriculum is reported in the TIMSS 2019 Encyclopedia.

Exhibit 13.5 presents fourth grade teachers’ reports about the TIMSS science topics that had been taught to students in fourth grade classrooms either prior to or during the year of the TIMSS assessment. The exhibit shows, for each country and the international average, the percentage of students whose teachers reported that the students had been taught each of the topics (before or during the school year), averaged across all topics in each science content domain, and also across all topics in all science domains. Exhibit 13.7 presents parallel information for the eighth grade, reported by teachers about the TIMSS science topics in the eighth grade assessment.

In the fourth grade, according to their teachers, 62 percent of students, on average, had been taught the TIMSS science topics overall. On average, 73 percent of students had been taught the TIMSS life science topics, and 58 percent and 60 percent had been taught the TIMSS physical science and Earth science topics, respectively. There was, however, considerable variation from content domain to content domain and from country to country, reflecting differing science curricular emphases.

In the eighth grade, on average, 72 percent of students had been taught the TIMSS science topics overall, according to their teachers. Close to three-quarters, on average, had been taught the TIMSS biology topics (74%) and chemistry topics (74%) by the eighth grade, according to their teachers, with slightly less having been taught the Earth science (71%) and physics (68%) topics. There was considerable variation across countries with respect to topic coverage by content domain.