(2) Effectiveness of Laboratory Experiences

The committee’s review of the evidence on attainment of the goals of laboratory experiences reveals a recent shift in research, reflecting some movement in laboratory instruction. Historically, laboratory experiences have been disconnected from the flow of classroom science lessons. Because this approach remains common today, we refer to these separate laboratory experiences as “typical” laboratory experiences. Reflecting this separation, researchers often engaged students in one or two experiments or other science activities and then conducted assessments to determine whether their understanding of the science concept underlying the activity had increased. Some studies compared the outcomes of these separate laboratory experiences with the outcomes of other forms of science instruction, such as lectures or discussions.

Over the past 10 years, a new body of research on the outcomes of laboratory experiences has been developing. Drawing on principles of learning derived from the cognitive sciences, researchers are investigating how to sequence science instruction, including laboratory experiences, in order to support students’ science learning. We propose the phrase “integrated instructional units” to describe these sequences of instruction. Integrated instructional units connect laboratory experiences with other types of science learning activities, including lectures, reading, and discussion. Students are engaged in framing research questions, making observations, designing and executing experiments, gathering and analyzing data, and constructing scientific arguments and explanations.

Integrated instructional units are designed to increase students’ ability to understand and apply science subject matter (often focusing on one important concept or principle) while also improving their scientific reasoning, interest in science, and understanding of the nature of science. Students are encouraged to discuss their existing ideas about the science concept and their emerging ideas during the course of their laboratory experiences, both with their peers and with the teacher. The sequence of laboratory experiences and other forms of instruction is designed to help students develop a more sophisticated understanding of both the science concept under study and the process through which scientific concepts are developed, evaluated, and refined.

The earlier body of research on typical laboratory experiences and the emerging research on integrated instructional units yield different findings about the effectiveness of laboratory experiences in advancing the goals identified by the committee. Research on typical laboratory experiences is methodologically weak and fragmented, making it difficult to draw precise conclusions. The weight of the evidence from research focused on the goals of developing scientific reasoning and cultivating student interest in science shows slight improvements in both after students participated in typical laboratory experiences. Research focused on the goal of student mastery of subject matter indicates that typical laboratory experiences are no more or less effective than other forms of science instruction (such as reading, lectures, or discussion).

A major limitation of the research on integrated instructional units is that most of the units have been used in small numbers of science classrooms. Only a few studies have addressed the challenges of implementing—and studying the effectiveness of—integrated instructional units on a wide scale. The studies conducted to date indicate that these sequences of laboratory experiences and other forms of instruction show greater effectiveness for these same three goals (compared with more traditional forms of science instruction): improving mastery of subject matter, developing scientific reasoning, and cultivating interest in science. Integrated instructional units also appear to be effective in helping diverse groups of students progress toward these three learning goals. Due to a lack of available studies, the committee was unable to draw conclusions about the extent to which either typical laboratory experiences or integrated instructional units might advance the other goals identified at the beginning of this chapter—enhancing understanding of the complexity and ambiguity of empirical work, acquiring practical skills, and developing teamwork skills.

The committee considers the evidence emerging from research on integrated instructional units sufficient to conclude: