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The degree of commitment to EHS programs varies widely among companies and governmental laboratories, as well. Many chemical companies recognize both their moral responsibility and their own self-interest in developing the best possible safety programs, extending them not just to employees but also to contractors. Others do little more than is absolutely required by law and regulations.

Unfortunately, bad publicity from a serious accident in one careless operation tarnishes the credibility of all committed supervisors and employees. Fortunately, chemical companies that excel in safety are becoming more common, and safety is often recognized as equal in importance to productivity, quality, profitability, and efficiency.

The industrial or governmental laboratory environment provides strong corporate structure and discipline for maintaining a well-organized safety program where the culture of safety is thoroughly understood, respected, and enforced from the highest level of management down. New employees coming from academic research laboratories are often surprised to discover the detailed planning and extensive safety checks that are required before running experiments. In return for their efforts, they learn the sense of personal security that goes with high professional standards.

Several key factors continue to affect the evolution of laboratory safety programs in industry, government, and academe. These factors include advances in technology, environmental impact, and changes in legal and regulatory requirements. In response to the increasingly high cost of chemical management, from procurement to waste disposal, a steady movement toward miniaturizing chemical operations exists in both teaching and research laboratories.

This trend has had a significant effect on laboratory design and has also reduced the costs associated with procurement, handling, and disposal of chemicals. Another trend—motivated at least partially by safety concerns—is the simulation of laboratory experiments by computer. Such programs are a valuable conceptual adjunct to laboratory training but are by no means a substitute for hands-on experimental work.

The scientific method

Only students who have been carefully educated through a series of hands-on experiments in the laboratory have the confidence and expertise needed to handle real laboratory procedures safely as they move on to advanced courses, research work, and eventually to their careers in industry, academe, health sciences, or government laboratories.

If a laboratory operation produces less waste, there is less waste to dispose of and less impact on the environment. A frequent, but not universal, corollary is that costs are also reduced. The narrow definition of source reduction includes only procedural and process changes that actually use less material and produce less waste. The definition does not include recycling or treatment to reduce the hazard of a waste. For example, changing to microscale techniques is considered source reduction, but recycling a solvent waste is not. Many advantages are gained by taking an active pollution prevention approach to laboratory work, and these are well documented throughout this book.

Some potential drawbacks do exist, and these are discussed as well and should be kept in mind when planning activities. For example, dramatically reducing the quantity of chemicals used in teaching laboratories may leave the student with an unrealistic appreciation of his or her behavior when using them on a larger scale.

Also, certain types of pollution prevention activities, such as solvent recycling, may cost far more in dollars and time than the potential value of recovered solvent. For more information about solvent recycling, see Chapter 5 , section 5. Before embarking on any pollution prevention program, it is worthwhile to review the options thoroughly with local EHS program managers and to review other organizations' programs to become fully aware of the relative merits of those options. Perhaps the most significant impediment to comprehensive waste reduction in laboratories is the element of scale.

Techniques that are practical and cost-effective on a gal or tank-car quantity of material may be highly unrealistic when applied to a g or milligram quantity, or vice versa. Evaluating the costs of both equipment and time becomes especially important when dealing with very small quantities. Changes in the legal and regulatory requirements over the past several decades have greatly affected laboratory operations.

Because of increased regulations, the collection and disposal of laboratory waste constitute major budget items in the operation of every chemical laboratory. The cost of accidents in terms of time and money spent on fines for regulatory violations and on litigation are significant. Of course, protection of students and research personnel from toxic materials is not only an economic necessity but an ethical obligation.

Laboratory accidents have resulted in serious, debilitating injuries and death, and the personal impact of such events cannot be forgotten. In line with some of the developments in laboratory practice, the committee recommends that OSHA review the standard in current context. In particular, the section on CHPs, In addition, this book provides guidance that could be a basis for strengthening the employee information and training section, Finally, the nonmandatory Appendix A of the Laboratory Standard was based on the original edition of Prudent Practices in the Laboratory , published in and currently out of print.

The committee recommends that the appendix be updated to reflect the changes in the current edition in both content and reference. The Laboratory Standard requires that every workplace conducting research or training where hazardous chemicals are used develop a CHP. This requirement has generated a greater awareness of safety issues at all educational science and technology departments and research institutions.

Although the priority assigned to safety varies widely among personnel within academic departments and divisions, increasing pressure comes from several other directions in addition to the regulatory agencies and to the potential for accident litigation. In some cases, significant fines have been imposed on principal investigators who received citations for safety violations.

These actions serve to increase the faculty's concern for laboratory safety. Boards of trustees or regents of educational institutions often include prominent industrial leaders who are aware of the increasing national concern with safety and environmental issues and are particularly sensitive to the possibility of institutional liability as a result of laboratory accidents.

Academic and government laboratories can be the targets of expensive lawsuits. The trustees assist academic officers both by helping to develop an appropriate institutional safety system with an effective EHS office and by supporting departmental requests for modifications of facilities to comply with safety regulations.

Federal granting agencies recognize the importance of sound laboratory practices and active laboratory safety programs in academe. Some require documentation of the institution's safety program as part of the grant proposal. When negligent or cavalier treatment of laboratory safety regulations jeopardizes everybody's ability to obtain funding, a powerful incentive is created to improve laboratory safety.

Over the years, chemical manufacturers have modernized their views of safety. Approaches to safety for all—including scientists with disabilities—have largely changed in laboratories as well. In the past, full mobility and full eyesight and hearing capabilities were considered necessary for safe laboratory operations. Now, encouraged legally by the adoption of the Americans with Disabilities Act of ADA and the ADA Amendments Act of , leaders in laboratory design and management realize that a nimble mind is more difficult to come by than modified space or instrumentation.

As a result, assistive technologies now exist to circumvent almost any inaccessibility, and laboratories can be equipped to take advantage of them. Many of the modifications to laboratory space and fixtures have benefits for all. Consider, as a single example, the assistance of ramps and an automatic door opener to all lab personnel moving a large cart or carrying two heavy containers.

It is a logical extension of the culture of safety to include a culture of accessibility. For information about compliance with the ADA in the laboratory, see Chapter 9 , section 9. Understanding of the nature of science. Laboratory experiences may help students to understand the values and assumptions inherent in the development and interpretation of scientific knowledge, such as the idea that science is a human endeavor that seeks to understand the material world and that scientific theories, models, and explanations change over time on the basis of new evidence.

Cultivating interest in science and interest in learning science. Developing teamwork abilities. Unlike the other goals, which coincide with the goals of science education more broadly and may be advanced through lectures, reading, or other forms of science instruction, laboratory experiences may be the only way to advance the goal of helping students understand the complexity and ambiguity of empirical work.

In reviewing evidence on the extent to which students may attain the goals of laboratory experiences listed above, the committee identified a recent shift in the research. Historically, laboratory experiences have been separate from the flow of classroom science instruction and often lacked clear learning goals. Some studies directly compared measures of student learning following laboratory experiences with measures of student learning following lectures, discussions, videotapes, or other methods of science instruction in an effort to determine which modes of instruction were most effective.

Over the past 10 years, some researchers have shifted their focus. Assuming that the study of the natural world requires opportunities to directly encounter that world, investigators are integrating laboratory experiences and other forms of instruction into instructional sequences in order to help students progress toward science learning goals.

These studies draw on principles of learning derived from the rapid growth in knowledge from cognitive research to address the question of how to design science instruction, including laboratory experiences, in order to support student learning. Given the complexity of these teaching and learning sequences, the committee struggled with how best to describe them.

The research reviewed by the committee indicated that these curricula not only integrate laboratory experiences in the flow of science instruction, but also integrate. In Chapter 4 , we argue that most U. The following sections briefly describe principles of learning derived from recent research in the cognitive sciences and their application in design of integrated instructional units. Recent research and development of integrated instructional units that incorporate laboratory experiences are based on a large and growing body of cognitive research.

This research has led to development of a coherent and multifaceted theory of learning that recognizes that prior knowledge, context, language, and social processes play critical roles in cognitive development and learning National Research Council, These four principles are summarized below.

The emerging integrated instructional units are designed to be learner-centered. This principle is based on research showing that effective instruction begins with what learners bring to the setting, including cultural practices and beliefs, as well as knowledge of academic content. Students come to the classroom with conceptions of natural phenomena that are based on their everyday experiences in the world. Although these conceptions are often reasonable and can provide satisfactory everyday explanations to students, they do not always match scientific explanations and break down in ways that students often fail to notice.

Teachers face the challenge of engaging with these intuitive ideas, some of which are more firmly rooted than others, in order to help students move toward a more scientific understanding. In this way, understanding scientific knowledge often requires a change in—not just an addition to—what students notice and understand about the world National Research Council, The developing integrated instructional units are based on the principle that learning is enhanced when the environment is knowledge-centered. That is, the laboratory experiences and other instruction included in integrated instructional units are designed to help students learn with understanding, rather than simply acquiring sets of disconnected facts and skills National Research Council, Research on student thinking about science shows a progression of ideas about scientific knowledge and how it is justified.

At the first stage, students perceive scientific knowledge as right or wrong. Several studies have shown that a large proportion of high school students are at the first stage in their views of scientific knowledge National Research Council, Knowledge-centered environments encourage students to reflect on their own learning progress metacognition. Learning is facilitated when individuals identify, monitor, and regulate their own thinking and learning. To be effective problem solvers and learners, students need to determine what they already know and what else they need to know in any given situation, including when things are not going as expected.

For example, students with better developed metacognitive strategies will abandon an unproductive problem-solving strategy very quickly and substitute a more productive one, whereas students with less effective metacognitive skills will continue to use the same strategy long after it has failed to produce results Gobert and Clement, A final aspect of knowledge-centered learning, which may be particularly relevant to integrated instructional units, is that the practices and activities in which people engage while learning shape what they learn.

Transfer the ability to apply learning in varying situations is made possible to the extent that knowledge and learning are grounded in multiple contexts. Transfer is more difficult when a concept is taught in a limited set of contexts or through a limited set of activities. By encountering the same concept at work in multiple contexts such as in laboratory experiences and in discussion ,. Another important principle of learning that has informed development of integrated instructional units is that assessment can be used to support learning. Cognitive research has shown that feedback is fundamental to learning, but feedback opportunities are scarce in most classrooms.

This research indicates that formative assessments provide students with opportunities to revise and improve the quality of their thinking while also making their thinking apparent to teachers, who can then plan instruction accordingly. Assessments must reflect the learning goals of the learning environment. If the goal is to enhance understanding and the applicability of knowledge, it is not sufficient to provide assessments that focus primarily on memory for facts and formulas. The Thinkertools science instructional unit discussed in the following section incorporates this principle, including formative self-assessment tools that help students advance toward several of the goals of laboratory experiences.

Research has shown that learning is enhanced in a community setting, when students and teachers share norms that value knowledge and participation see Cobb et al. A community-centered classroom environment may not be organized in traditional ways. For example, in science classrooms, the teacher is often the sole authority and arbiter of scientific knowledge, placing students in a relatively passive role Lemke, The instructional units discussed below have attempted to restructure the social organization of the classroom and encourage students and the teacher to interact and learn from each other.

The learning principles outlined above have begun to inform design of integrated instructional units that include laboratory experiences with other types of science learning activities. These integrated instructional units were. The research programs are beginning to document the details of student learning, development, and interaction when students are given systematic support—or scaffolding—in carefully structured social and cognitive activities. Emerging research on these integrated instructional units provides guidance about how to design effective learning environments for real-world educational settings see Linn, Davis, and Bell, a; Cobb et al.

Integrated instructional units interweave laboratory experiences with other types of science learning activities, including lectures, reading, and discussion. Students are engaged in framing research questions, designing and executing experiments, gathering and analyzing data, and constructing arguments and conclusions as they carry out investigations. With respect to laboratory experiences, these instructional units share two key features. The first is that specific laboratory experiences are carefully selected on the basis of research-based ideas of what students are likely to learn from them.

The second is that laboratory experiences are explicitly linked to and integrated with other learning activities in the unit. The assumption behind this second feature is that just because students do a laboratory activity, they may not necessarily understand what they have done. Nascent research on integrated instructional units suggests that both framing a particular laboratory experience ahead of time and following it with activities that help students make sense of the experience are crucial in using a laboratory experience to support science learning.

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Chemistry That Applies CTA is a week integrated instructional unit designed to help students in grades understand the law of conservation. Created by researchers at the Michigan Department of Education Blakeslee et al.

10 Easy Science Experiments - That Will Amaze Kids

Student groups explore four chemical reactions—burning, rusting, the decomposition of water, and the volcanic reaction of baking soda and vinegar. They cause these reactions to happen, obtain and record data in individual notebooks, analyze the data, and use evidence-based arguments to explain the data. The instructional unit engages the students in a carefully structured sequence of hands-on laboratory investigations interwoven with other forms of instruction Lynch, Researchers at George Washington University, in a partnership with Montgomery County public schools in Maryland, are currently conducting a five-year study of the feasibility of scaling up effective integrated instructional units, including CTA Lynch, Kuipers, Pyke, and Szesze, in press.

In , CTA was implemented in five highly diverse middle schools that were matched with five comparison schools using traditional curriculum materials in a quasi-experimental research design. All 8th graders in the five CTA schools, a total of about 1, students, participated in the CTA curriculum, while all 8th graders in the matched schools used the science curriculum materials normally available.

Students were given pre- and posttests. In , the study was replicated in the same five pairs of schools. In both years, students who participated in the CTA curriculum scored significantly higher than comparison students on a posttest. Average scores of students who participated in the CTA curriculum showed higher levels of fluency with the concept of conservation of matter Lynch, However, because the concept is so difficult, most students in both the treatment and control group still have misconceptions, and few have a flexible, fully scientific understanding of the conservation of matter.

The effect sizes were largest among three subgroups considered at risk for low science achievement, including Hispanic students, low-income students, and English language learners. Building on these positive results, ThinkerTools was expanded to focus not only on mastery of these laws of motion but also on scientific reasoning and understanding of the nature of science White and Frederiksen, In the week unit, students were guided to reflect on their own thinking and learning while they carry out a series of investigations.

The integrated instructional unit was designed to help them learn about science processes as well as about the subject of force and motion. The instructional unit supports students as they formulate hypotheses, conduct empirical investigations, work with conceptually analogous computer simulations, and refine a conceptual model for the phenomena. Across the series of investigations, the integrated instructional unit introduces increasingly complex concepts.

Formative assessments are integrated throughout the instructional sequence in ways that allow students to self-assess and reflect on core aspects of inquiry and epistemological dimensions of learning. Researchers investigated the impact of Thinker Tools in 12 7th, 8th, and 9th grade classrooms with 3 teachers and students. In this assessment, students were engaged in a thought experiment that asked them to conceptualize, design, and think through a hypothetical research study.

Gains in scores for students in the reflective self-assessment classes and control classrooms were compared. Results were also broken out by students categorized as high and low achieving, based on performance on a standardized test conducted before the intervention. Students in the reflective self-assessment classes exhibited greater gains on a test of investigative skills. This was especially true for low-achieving students.

The researchers further analyzed specific components of the associated scientific processes—formulation of hypotheses, designing an experiment, predicting results, drawing conclusions from made-up results, and relating those conclusions back to the original hypotheses. Students in the reflective-self-assessment classes did better on all of these components than those in control classrooms, especially on the more difficult components drawing conclusions and relating them to the original hypotheses. Beginning in , a large group of technologists, classroom teachers, and education researchers developed the Computer as Learning Partner CLP.

Over 10 years, the team developed and tested eight versions of a week unit on thermodynamics. The project engaged students in a sequence of laboratory experiences supported by computers, discussions, and other forms of science instruction.

The 10 Most Important Lab Safety Rules

For example, computer images and words prompted students to make predictions about heat and conductivity and perform experiments using temperature-sensitive probes to confirm or refute their predictions. Students were given tasks related to scientific phenomena affecting their daily lives—such as how to keep a drink cold for lunch or selecting appropriate clothing for hiking in the mountains—as a way to motivate their interest and curiosity.

Prudent Practices in the Laboratory: Handling and Management of Chemical Hazards: Updated Version.

Over 10 years of study and revision, the integrated instructional unit proved increasingly effective in achieving its stated learning goals. Before the sequenced instruction was introduced, only 3 percent of middle school students could adequately explain the difference between heat and temperature. Eight versions later, about half of the students participating in CLP could explain this difference, representing a percent increase in achievement.

In addition, nearly percent of students who participated in the final version of the instructional unit demonstrated understanding of conductors Linn and Songer, By comparison, only 25 percent of a group of undergraduate chemistry students at the University of California at Berkeley could adequately explain the difference between heat and temperature. Longitudinal studies of CLP participants revealed that, among those who went on to take high school physics, over 90 percent thought science was relevant to their lives.

And 60 percent could provide examples of scientific phenomena in their daily lives. By comparison, only 60 percent of high school physics students who had not participated in the unit during middle school thought science was relevant to their lives, and only 30 percent could give examples in their daily lives Linn and Hsi, In reviewing both bodies of research, we aim to specify how laboratory experiences can further each of the science learning goals outlined at the beginning of this chapter. Our review was complicated by weaknesses in the earlier research on typical laboratory experiences, isolated from the stream of instruction Hofstein and Lunetta, Second, many studies were weak in the selection and control of variables.

Investigators failed to examine or report important variables relating to student abilities and attitudes. They also did not give enough attention to extraneous factors that might affect student outcomes, such as instruction outside the laboratory. Third, the studies of typical laboratory experiences usually involved a small group of students with little diversity, making it difficult to generalize the results to the large, diverse population of U.

Fourth, investigators did not give enough attention to the adequacy of the instruments used to measure student outcomes. As an example, paper and pencil tests that focus on testing mastery of subject matter, the most frequently used assessment, do not capture student attainment of all of the goals we have identified. Such tests are not able to measure student progress toward goals that may be unique to laboratory experiences, such as developing scientific reasoning, understanding the complexity and ambiguity of empirical work, and development of practical skills.

Finally, most of the available research on typical laboratory experiences does not fully describe these activities. Few studies have examined teacher behavior, the classroom learning environment, or variables identifying teacher-student interaction. In addition, few recent studies have focused on laboratory manuals—both what is in them and how they are used.

Research on the intended design of laboratory experiences, their implementation, and whether the implementation resembles the initial design would provide the understanding needed to guide improvements in laboratory instruction. However, only a few studies of typical laboratory experiences have measured the effectiveness of particular laboratory experiences in terms of both the extent.

10 Important Lab Safety Rules

We also found weaknesses in the evolving research on integrated instructional units. First, these new units tend to be hothouse projects; researchers work intensively with teachers to construct atypical learning environments. While some have been developed and studied over a number of years and iterations, they usually involve relatively small samples of students. Only now are some of these efforts expanding to a scale that will allow robust generalizations about their value and how best to implement them. Second, these integrated instructional units have not been designed specifically to contrast some version of laboratory or practical experience with a lack of such experience.

Researchers commonly aim to document the complex interactions between and among students, teachers, laboratory materials, and equipment in an effort to develop profiles of successful interventions Cobb et al. A final note on the review of research: the scope of our study did not allow for an in-depth review of all of the individual studies of laboratory education conducted over the past 30 years.

Fortunately, three major reviews of the literature from the s, s, and s are available Lazarowitz and Tamir, ; Lunetta, ; Hofstein and Lunetta, The committee relied on these reviews in our analysis of studies published before To identify studies published between and , the committee searched electronic databases. To supplement the database search, the committee commissioned three experts to review the nascent body of research on integrated instructional units Bell, ; Duschl, ; Millar, We also invited researchers who are currently developing, revising, and studying the effectiveness of integrated instructional units to present their findings at committee meetings Linn, ; Lynch, All of these activities yielded few studies that focused on the high school level and were conducted in the United States.

For this reason, the committee expanded the range of the literature considered to include some studies targeted at middle school and some international studies. We included stud-. In drawing conclusions from studies that were not conducted at the high school level, the committee took into consideration the extent to which laboratory experiences in high school differ from those in elementary and postsecondary education. Developmental differences among students, the organizational structure of schools, and the preparation of teachers are a few of the many factors that vary by school level and that the committee considered in making inferences from the available research.

Similarly, when deliberating on studies conducted outside the United States, we considered differences in the science curriculum, the organization of schools, and other factors that might influence the outcomes of laboratory education. Claims that typical laboratory experiences help students master science content rest largely on the argument that opportunities to directly interact with, observe, and manipulate materials will help students to better grasp difficult scientific concepts.


It is believed that these experiences will force students to confront their misunderstandings about phenomena and shift toward more scientific understanding. Despite these claims, there is almost no direct evidence that typical laboratory experiences that are isolated from the flow of science instruction are particularly valuable for learning specific scientific content Hofstein and Lunetta, , ; Lazarowitz and Tamir, White points out that many major reviews of science education from the s and s indicate that laboratory work does little to improve understanding of science content as measured by paper and pencil tests, and later studies from the s and early s do not challenge this view.

Other studies indicate that typical laboratory experiences are no more effective in helping students master science subject matter than demonstrations in high school biology Coulter, , demonstration and discussion Yager, Engen, and Snider, , and viewing filmed experiments in chemistry Ben-Zvi, Hofstein, Kempa, and Samuel, In contrast to most of the research, a single comparative study Freedman, found that students who received regular laboratory instruction over the course of a school year performed better on a test of physical science knowledge than a control group of students who took a similar physical science course without laboratory activities.

Clearly, most of the evidence does not support the argument that typical laboratory experiences lead to improved learning of science content. More specifically, concrete experiences with phenomena alone do not appear to. However, the students remained unable to develop a fully scientific mental model of a circuit system.

The authors suggested that greater engagement with conceptual organizers, such as analogies and concept maps, could have helped students develop more scientific understandings of basic electricity. Several researchers, including Dupin and Joshua , have reported similar findings. Studies indicate that students often hold beliefs so intensely that even their observations in the laboratory are strongly influenced by those beliefs Champagne, Gunstone, and Klopfer, , cited in Lunetta, ; Linn, Students tend to adjust their observations to fit their current beliefs rather than change their beliefs in the face of conflicting observations.

Current integrated instructional units build on earlier studies that found integration of laboratory experiences with other instructional activities enhanced mastery of subject matter Dupin and Joshua, ; White and Gunstone, , cited in Lunetta, A recent review of these and other studies concluded Hofstein and Lunetta, , p. Integrated instructional units often focus on complex science topics that are difficult for students to understand. For this reason, the sequenced units incorporate instructional activities specifically designed to confront intuitive conceptions and provide an environment in which students can construct normative conceptions.

In order to help students link formal, scientific concepts to real. Emerging studies indicate that exposure to these integrated instructional units leads to demonstrable gains in student mastery of a number of science topics in comparison to more traditional approaches. Integrated instructional units in biology have enhanced student mastery of genetics Hickey, Kindfield, Horwitz, and Christie, and natural selection Reiser et al.

A chemistry unit has led to gains in student understanding of stoichiometry Lynch, Many, but not all, of these instructional units combine computer-based simulations of the phenomena under study with direct interactions with these phenomena. The role of technology in providing laboratory experiences is described later in this chapter. While philosophers of science now agree that there is no single scientific method, they do agree that a number of reasoning skills are critical to research across the natural sciences.

These reasoning skills include identifying questions and concepts that guide scientific investigations, designing and conducting scientific investigations, developing and revising scientific explanations and models, recognizing and analyzing alternative explanations and models, and making and defending a scientific argument. It is not necessarily the case that these skills are sequenced in a particular way or used in every scientific investigation.

Instead, they are representative of the abilities that both scientists and students need to investigate the material world and make meaning out of those investigations. Early research on the development of investigative skills suggested that students could learn aspects of scientific reasoning through typical laboratory instruction in college-level physics Reif and St.

John, , cited in Hofstein and Lunetta, and in high school and college biology Raghubir, ; Wheatley, , cited in Hofstein and Lunetta, More recent research, however, suggests that high school and college science teachers often emphasize laboratory procedures, leaving little time for discussion of how to plan an investigation or interpret its results Tobin, ; see Chapter 4. Taken as a whole, the evidence indicates that typical laboratory work promotes only a few aspects of the full process of scientific reasoning—making observations and organizing, communicating, and interpreting data gathered from these observations.

Typical laboratory experiences appear to have little effect on more complex aspects of scientific reasoning, such as the capacity to formulate research questions, design experiments, draw conclusions from observational data, and make inferences Klopfer, , cited in White, Research developing from studies of integrated instructional units indicates that laboratory experiences can play an important role in developing all aspects of scientific reasoning, including the more complex aspects, if the laboratory experiences are integrated with small group discussion, lectures, and other forms of science instruction.

With carefully designed instruction that incorporates opportunities to conduct investigations and reflect on the results, students as young as 4th and 5th grade can develop sophisticated scientific thinking Lehrer and Schauble, ; Metz, Kuhn and colleagues have shown that 5th graders can learn to experiment effectively, albeit in carefully controlled domains and with extended supervised practice Kuhn, Schauble, and Garcia-Mila, Explicit instruction on the purposes of experiments appears necessary to help 6th grade students design them well Schauble, Giaser, Duschl, Schulze, and John, These studies suggest that laboratory experiences must be carefully designed to support the development of scientific reasoning.

Given the difficulty most students have with reasoning scientifically, a number of instructional units have focused on this goal. Evidence from several studies indicates that, with the appropriate scaffolding provided in these units, students can successfully reason scientifically. They can learn to design experiments Schauble et al. Integrated instructional units seem especially beneficial in developing scientific reasoning skills among lower ability students White and Frederiksen, Recently, research has focused on an important element of scientific reasoning—the ability to construct scientific arguments.

Developing, revising, and communicating scientific arguments is now recognized as a core scientific practice Driver, Newton, and Osborne, ; Duschl and Osborne, Such efforts have taken many forms. Students designed an investigation to determine which school drinking fountain had the best-tasting water.

The students designed data collection protocols, collected and analyzed their data, and then argued about their findings Rosebery et al. The Knowledge Integration Environment project asked middle school students to examine a common set of evidence to debate competing hypotheses about light propagation. Overall, most students learned the scientific concept that light goes on forever , although those who made better arguments learned more than their peers Bell and Linn, These and other examples e.

Science educators and researchers have long claimed that learning practical laboratory skills is one of the important goals for laboratory experiences and that such skills may be attainable only through such experiences White, ; Woolnough, However, development of practical skills has been measured in research less frequently than mastery of subject matter or scientific reasoning.

Such practical outcomes deserve more attention, especially for laboratory experiences that are a critical part of vocational or technical training in some high school programs. When a primary goal of a program or course is to train students for jobs in laboratory settings, they must have the opportunity to learn to use and read sophisticated instruments and carry out standardized experimental procedures. The critical questions about acquiring these skills through laboratory experiences may not be whether laboratory experiences help students learn them, but how the experiences can be constructed so as to be most effective in teaching such skills.

Some research indicates that typical laboratory experiences specifically focused on learning practical skills can help students progress toward other goals. For example, one study found that students were often deficient in the simple skills needed to successfully carry out typical laboratory activities, such as using instruments to make measurements and collect accurate data Bryce and Robertson, This research suggests that development of practical skills may increase the probability that students will achieve the intended results in laboratory experiences.

Achieving the intended results of a laboratory activity is a necessary, though not sufficient, step toward effectiveness in helping students attain laboratory learning goals. Some research on typical laboratory experiences indicates that girls handle laboratory equipment less frequently than boys, and that this tendency is associated with less interest in science and less self-confidence in science ability among girls Jovanovic and King, It is possible that helping girls to develop instrumentation skills may help them to participate more actively and enhance their interest in learning science.

Studies of integrated instructional units have not examined the extent to which engagement with these units may enhance practical skills in using laboratory materials and equipment. This reflects an instructional emphasis on helping students to learn scientific ideas with real understanding and on developing their skills at investigating scientific phenomena, rather than on particular laboratory techniques, such as taking accurate measurements or manipulating equipment.

There is no evidence to suggest that students do not learn practical skills through integrated instructional units, but to date researchers have not assessed such practical skills. The general public understanding of science is similarly inaccurate. Laboratory experiences are considered the primary mecha-. Research on student understanding of the nature of science provides little evidence of improvement with science instruction Lederman, ; Driver et al.

Younger students tend to believe that experiments yield direct answers to questions; during middle and high school, students shift to a vague notion of experiments being tests of ideas. Only a small number of students appear to leave high school with a notion of science as model-building and experimentation, in an ongoing process of testing and revision Driver et al.

The conclusion that most experts draw from these results is that the isolated nature and rote procedural focus of typical laboratory experiences inhibits students from developing robust conceptions of the nature of science. Consequently, some have argued that the nature of science must be an explicit target of instruction Khishfe and Abd-El-Khalick, ; Lederman, Abd-El-Khalick, Bell, and Schwartz, As discussed above, there is reasonable evidence that integrated instructional units help students to learn processes of scientific inquiry.

However, such instructional units do not appear, on their own, to help students develop robust conceptions of the nature of science. Students engaged in the BGuILE science instructional unit showed no gains in understanding the nature of science from their participation, and they seemed not even to see their experience in the unit as necessarily related to professional science Sandoval and Morrison, These findings and others have led to the suggestion that the nature of science must be an explicit target of instruction Lederman et al.

There is evidence from the ThinkerTools science instructional unit that by engaging in reflective self-assessment on their own scientific investiga-. Instead, they saw science as meaningful and explicable. The available research leaves open the question of whether or not these experiences help students to develop an explicit, reflective conceptual framework about the nature of science.

Studies of the effect of typical laboratory experiences on student interest are much rarer than those focusing on student achievement or other cognitive outcomes Hofstein and Lunetta, ; White, The number of studies that address interest, attitudes, and other affective outcomes has decreased over the past decade, as researchers have focused almost exclusively on cognitive outcomes Hofstein and Lunetta, Among the few studies available, the evidence is mixed.

Some studies indicate that laboratory experiences lead to more positive attitudes Renner, Abraham, and Birnie, ; Denny and Chennell, Other studies show no relation between laboratory experiences and affect Ato and Wilkinson, ; Freedman, , and still others report laboratory experiences turned students away from science Holden, ; Shepardson and Pizzini, There are, however, two apparent weaknesses in studies of interest and attitude Hofstein and Lunetta, One is that researchers often do not carefully define interest and how it should be measured.

Consequently, it is unclear if students simply reported liking laboratory activities more than other classroom activities, or if laboratory activities engendered more interest in science as a field, or in taking science courses, or something else. When students do not understand the goals of experiments or laboratory investigations, negative consequences for learning occur Schauble et al. In fact, students often do not make important connections between the purpose of a typical laboratory investigation and the design of the experiments.

They do not connect the experiment with what they have done earlier, and they do not note the discrepancies among their own concepts, the concepts of their peers, and those of the science community Champagne et al. The SLEI, which has been validated cross-nationally, measures five dimensions of the laboratory environment: student cohesiveness, open-endedness, integration, rule clarity, and material environment see Table for a description of each scale.

All five dimensions appear to be positively related with student attitudes, although the. Extent to which the laboratory activities emphasize an open-ended, divergent approach to experimentation. Extent to which laboratory activities are integrated with nonlaboratory and theory classes. Reprinted with permission of Wiley-Liss, Inc.

In some populations, there is a negative relation to attitudes Fraser et al. Research using the SLEI indicates that positive student attitudes are particularly strongly associated with cohesiveness the extent to which students know, help, and are supportive of one another and integration the extent to which laboratory activities are integrated with nonlaboratory and theory classes Fraser et al.

When evidence is available, it suggests that students who participate in these units show greater interest in and more positive attitudes toward science. For example, in a study of ThinkerTools, completion of projects was used as a measure of student interest. The rate of submitting completed projects was higher for students in the ThinkerTools curriculum than for those in traditional instruction.

This was true for all grades and ability levels White and. Frederiksen, Students who participated in the CTA curriculum had higher levels of basic engagement active participation in activities and were more likely to focus on learning from the activities than students in the control group Lynch et al. This positive effect on engagement was especially strong among low-income students.

Students who participated in CLP during middle school, when surveyed years later as high school seniors, were more likely to report that science is relevant to their lives than students who did not participate Linn and Hsi, Further research is needed to illuminate which aspects of this instructional unit contribute to increased interest. Teamwork and collaboration appear in research on typical laboratory experiences in two ways.

First, working in groups is seen as a way to enhance student learning, usually with reference to literature on cooperative learning or to the importance of providing opportunities for students to discuss their ideas. Second and more recently, attention has focused on the ability to work in groups as an outcome itself, with laboratory experiences seen as an ideal opportunity to develop these skills. The focus on teamwork as an outcome is usually linked to arguments that this is an essential skill for workers in the 21st century Partnership for 21st Century Skills, There is considerable evidence that collaborative work can help students learn, especially if students with high ability work with students with low ability Webb and Palincsar, Collaboration seems especially helpful to lower ability students, but only when they work with more knowledgeable peers Webb, Nemer, Chizhik, and Sugrue, Building on this research, integrated instructional units engage students in small-group collaboration as a way to encourage them to connect what they know either from their own experiences or from prior instruction to their laboratory experiences.

Often, individual students disagree about prospective answers to the questions under investigation or the best way to approach them, and collaboration encourages students to articulate and explain their reasoning. A number of studies suggest that such collaborative investigation is effective in helping students to learn targeted scientific concepts Coleman, ; Roschelle, Extant research lacks specific assessment of the kinds of collaborative skills that might be learned by individual students through laboratory work.

The assumption appears to be that if students collaborate and such collaborations are effective in supporting their conceptual learning, then they are probably learning collaborative skills, too. The two bodies of research—the earlier 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.

In general, the nascent body of research on integrated instructional units offers the promise that laboratory experiences embedded in a larger stream of science instruction can be more effective in advancing these goals than are typical laboratory experiences see Table Research on the effectiveness of typical laboratory experiences is methodologically weak and fragmented.

The limited evidence available suggests that typical laboratory experiences, by themselves, are neither better nor worse than other methods of science instruction for helping students master science subject matter. Studies have demonstrated increases in student mastery of complex topics in physics, chemistry, and biology. Typical laboratory experiences appear, based on the limited research available, to support some aspects of scientific reasoning; however, typical laboratory experiences alone are not sufficient for promoting more sophisticated scientific reasoning abilities, such as asking appropriate questions,.

Research on integrated instructional units provides evidence that the laboratory experiences and other forms of instruction they include promote development of several aspects of scientific reasoning, including the ability to ask appropriate questions, design experiments, and draw inferences.

In contrast, some studies find that participating in integrated instructional units that are designed specifically with this goal in mind enhances understanding of the nature of science. Studies conducted to date also suggest that the units are effective in helping diverse groups of students attain these three learning goals.

In contrast, the earlier research on typical laboratory experiences indicates that such typical laboratory experiences are neither better nor worse than other forms of science instruction in supporting student mastery of subject matter. Due to a lack of available studies, the committee was unable to draw conclusions about the extent to which either typical laboratory experiences or laboratory experiences incorporated into 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 three bodies of research we have discussed—research on how people learn, research on typical laboratory experiences, and developing research on how students learn in integrated instructional units—yield information that promises to inform the design of more effective laboratory experiences. The committee considers the emerging evidence sufficient to suggest four general principles that can help laboratory experiences achieve the goals outlined above. It must be stressed, however, that research to date has not described in much detail how these principles can be implemented nor how each principle might relate to each of the educational goals of laboratory experiences.

Effective laboratory experiences have clear learning goals that guide the design of the experience. Ideally these goals are clearly communicated to students. Without a clear understanding of the purposes of a laboratory activity, students seem not to get much from it. Some of this is due to changes in how food is processed, some is due to the fact that with global trade there is greater variation across crop growing environments and food production operations, and some is due to scientific advances that have allowed us to better understand the factors that impact food safety. To make effective policy decisions that protect the public health, FDA needs to understand the relative risks posed by foodborne pathogens, chemical contaminants, chemical and microbial toxins, changes in nutrient intake, and other health concerns.

It must also understand the likely public health impact of different strategies to mitigate these risks. To accomplish this FDA conducts risk assessments and safety assessments. These assessments use a scientific approach to understand and to quantify specific food safety risks. For risk assessments, FDA develops mathematical models and other tools that simulate a microbial or chemical food safety problem, integrating the many factors that contribute to it. For safety assessments, FDA analyzes existing studies to calculate the levels of contaminants that are likely to cause harm.

Once a risk is assessed FDA can use that information to prioritize the risk against other public health risks and to determine and implement effective risk management strategies designed to reduce the likelihood of illness or injury. Completed risk assessments, safety assessments, and other information related to risk analyses can be found on the FDA foods program's risk and safety assessment web page. FDA is also engaged in a number of efforts to gather information about the foods U.