© 2001 International Association for the Evaluation of Educational Achievement (IEA)
What Activities Do Students Do in Their Science Lessons?
Because it can affect pedagogical strategies, class size is shown in Exhibit 6.7. Teachers reports on the size of their eighth-grade science class reveal that across countries the average was 31 students, but there was considerable variation even among the higher-performing countries from 43 students in Korea to 20 in Belgium (Flemish). Average class size was relatively uniform across all of the Benchmarking entities, ranging from 23 to 32 students. The relationship between class size and achievement is difficult to disentangle, given the variety of policies and practices and the fact that smaller classes can be used for both advanced and remedial learning. It makes sense, however, that teachers may have an easier time managing and conducting more student centered instructional activities with smaller classes.
Extensive research about class size in relation to achievement indicates that the existence of such a relationship is dependent on the situation.(4) Dramatic reductions in class size can be related to gains in achievement, but the chief effects of smaller classes often are in relation to teacher attitudes and instructional behaviors. Also, the research is more consistent in suggesting that reductions in class size have the potential to help students in the primary grades. The TIMSS 1999 data support the complexity of this issue. Four of the five highest-performing countries Chinese Taipei, Singapore, Japan, and Korea were among those with the largest science classes. Within countries, several show little or no relationship between achievement and class size, often because students are mostly all in classes of similar size. Within other countries, there appears to be a curvilinear relationship, or those students with higher achievement appear to be in larger classes. In some countries, larger classes may represent the more usual situation for science teaching, with smaller classes used primarily for students needing remediation or for those students in the less-advanced tracks.
Exhibit 6.8 presents a profile of the activities most commonly encountered in science classes around the world, as reported by science teachers. On average internationally, the most common activity was teacher lecture (24 percent of class time), followed by students conducting experiments (15 percent) and teacher-guided student practice (14 percent). Re-teaching and clarification of content and procedures, student independent practice, tests and quizzes, and teacher demonstrations of experiments each occupied 10 percent of class time. In general for the United States as a whole and the Benchmarking entities, teachers reports on the frequency of these activities matched the international profile. According to US science teachers, class time is spent as follows: 19 percent on lecture style teacher presentation; 23 percent on teacher-guided or independent student practice; 17 percent on students conducting experiments; eight percent on teachers demonstrating experiments; nine percent on re-teaching and clarification; nine percent on tests and quizzes, eight percent on homework review; six percent on administrative tasks; and three percent on other activities.
As shown in Exhibit 6.9, most students internationally (80 percent on average in general-science countries) agreed with teachers reports about the prevalence of teacher-guided activities, saying that their teachers frequently showed them how to do science problems. Approximately 70 percent of the students in the United States overall and in most of the Benchmarking entities reported this also. According to students, working independently on worksheets or textbooks also occurred frequently internationally (56 percent), and was even more pervasive throughout the Benchmarking entities, where between 70 and 85 percent in most entities reported doing this activity almost always or pretty often. As for working on science projects, the Benchmarking entities typically were above the international average (51 percent), ranging from 49 to 77 percent.
Compared with students internationally, eighth graders in each of the Benchmarking jurisdictions and in the United States overall reported an unusually large amount of classroom time devoted to working on homework. Internationally, 51 percent of the students reported frequently discussing their completed homework in science class. The figure for the United States was 63 percent, and it ranged from 52 percent in Texas to 82 percent in Naperville for the Benchmarking jurisdictions. A slightly greater difference was evident for frequently beginning homework in class 41 percent internationally compared with 57 percent for the United States. In the Benchmarking jurisdictions, from 41 to 74 percent of the students reported beginning their homework in class almost always or pretty often.
As might be anticipated, students reported that use of the board was an extremely common presentational mode in science class (see Exhibit 6.10). On average internationally for the general-science countries, 86 percent of students reported that teachers used the board at least pretty often, and 42 percent reported that students did so. Using the board seems to be less common in the United States, especially for students (29 percent). In the United States, use of an overhead projector is a popular presentational mode, especially for teachers 59 percent compared with 32 percent internationally. This mode was used frequently for more than 70 percent of the students in Maryland, North Carolina, Oregon, South Carolina, Texas, the Academy School District, Guilford County, Montgomery County, and Rochester. Use of a computer by the teacher to demonstrate ideas in science was more prevalent in the US (20 percent of students) than internationally (10 percent), and among Benchmarking entities ranged from 12 percent in Chicago and Guilford County to 28 percent in Jersey City and Montgomery County.
Effective science instruction requires the teacher to guide, focus, challenge, and encourage student learning. Problem-solving activities typically call upon students to use higher-order thinking skills. To examine the emphasis on reasoning and problem-solving in science class, TIMSS created an index of teachers emphasis on scientific reasoning and problem-solving (ESRPS). As shown in Exhibit 6.11, the index is based on teachers reports about how often they asked students to explain the reasoning behind an idea, represent and analyze relationships using tables, charts, and graphs, work on problems for which there is no immediately obvious method of solution, write explanations about what was observed and why it happened, and put events or objects in order and give a reason for the organization. Students were placed in the high category if, on average, they were asked to do these activities in most of their lessons. The medium level represents students asked to do these activities in some to most lessons, and students in the low category did them only in some lessons or rarely.
On average internationally, 16 percent of students had teachers who placed a high emphasis on scientific reasoning and problem-solving, ranging from four percent in Belgium (Flemish) to about one-third in Japan among the comparison countries. While the emphasis on scientific reasoning and problem-solving was associated with achievement in some countries, there was no strong or consistent relationship internationally or across entities. There was tremendous variation among the Benchmarking participants on this index, ranging from 63 percent of students in the high category in Naperville to nine percent or less in Chicago, Rochester, the Michigan Invitational Group, and Idaho.
Exhibit R3.7 in the reference section shows the percentages of students asked in most or every lesson to engage in each of the activities included in the problem-solving index. The most common problem-solving activity was for teachers to ask students to explain the reasoning behind an idea. On average internationally, 68 percent of students had teachers who asked them to do this in most or every lesson. On average also, a majority of students (52 percent) were asked to write explanations about what was observed and why it happened in most or every lesson, but only 15 percent were asked to work on problems for which there was no immediately obvious method of solution. In the United States and among Benchmarking participants generally, teachers more often asked students to explain the reasoning behind an idea (80 percent of students in the United States, and up to 100 percent in Naperville), but otherwise approximated the international averages.
The choices teachers make determine, to a large extent, what students learn. An important aspect of teaching science is the emphasis placed on scientific investigation. In order to measure this, TIMSS created an index of emphasis on conducting experiments in science classes (ECES), shown in Exhibit 6.12. The index is based on students and teachers reports of the frequency of the teacher demonstrating experiments and the students conducting experiments or practical investigations. A high level indicates that the teacher reported that at least 25 percent of class time is spent on the teacher demonstrating or students conducting experiments, and the student reported that these occur almost always or pretty often. A low level indicates that the teacher reported that 10 percent or less of class time is spent on the teacher demonstrating or students conducting experiments, and the student reported that these occur once in a while or never. The middle category includes all other combinations of responses.
Internationally on average, 38 percent of students in countries with general/integrated science were in classes with a high emphasis on experiments, ranging from two percent in Italy to 78 percent in Hong Kong. There was great variation among the Benchmarking participants also, from a high of 79 percent in Naperville to a low of 17 percent in the Delaware Science Coalition. In general, lower percentages of students in the high category were found in the countries with separate sciences, but this varied across science subjects, with the greatest emphasis on experiments in the physical sciences. Earth science had the least emphasis on experiments. Across countries, 52 percent of earth science students were in the low category, but only 21 percent of students in biology, five percent in physics and chemistry, and three percent in general/integrated science had classes with low emphasis on experiments.
Exhibits R3.8 and 3.9 in the reference section summarize students responses to the questions on the frequency of teachers demonstrating and students conducting experiments that were included in the index of emphasis on conducting experiments. On average internationally, 71 percent of students in general/integrated science reported that their teachers demonstrate experiments almost always or pretty often. Only 29 percent of Italian students reported that their teachers did so, compared with 91 percent of the students in England. The United States and the Benchmarking participants generally were close to the international average. Among separate-science countries, teacher demonstrations of experiments were reported most often in chemistry (68 percent) and physics (61 percent), and less frequently in biology (42 percent) and earth science (19 percent).
Students reports on the frequency with which they conduct experiments or practical investigations in class show a similar pattern across science subjects but a lower frequency than for teachers demonstration of experiments. Internationally, 57 percent of students in countries with general/integrated science reported that they do an experiment or practical investigation almost always or pretty often. Across countries with separate sciences, only 15 percent of the students in earth science, 27 percent in biology, and 39 percent in physics and chemistry reported doing experiments this frequently. In the United States, 65 percent of students reported frequently doing experiments or practical investigations, and among Benchmarking participants the percentage ranged from 44 percent in Chicago to more than 85 percent in the Academy School District, First in the World, and Naperville.
Teachers were not asked about the emphasis placed on using things from everyday life in solving science problems, but students were (see Exhibit R3.10). In most of the countries, students reported a moderate emphasis on doing this type of problem in science class. Almost half (49 percent), on average internationally, said these activities occur once in a while or pretty often in science class. The figures were comparable for the United States and most Benchmarking jurisdictions. More than half the students in Connecticut, Maryland, North and South Carolina, Chicago, the Fremont/Lincoln/Westside Public Schools, Guilford County, Jersey City, Miami-Dade, Naperville, and Rochester reported that they use things from everyday life in solving science problems almost always or pretty often.
TIMSS 1999 Benchmarking is a project of the
International Study Center
Boston College, Lynch School of Education