America has grown accustomed to being a leader in technological innovation, thanks in large part to its human capital (see, e.g., Goldin and Katz 2008). Historically, American workers have been among the best educated and most skilled in the world, and the scientists and engineers employed by US businesses and universities (whether they were born here or abroad) have been at the forefront in scientific discovery.
But this advantage cannot be taken for granted. Not for the first time, concerns are being raised about whether the US educational system is continuing this tradition. At the height of the Cold War, fears aroused in the wake of the Soviet Union’s Sputnik launch inspired a massive investment of public resources in improving the training of US scientists and engineers. In today’s more multipolar world, American institutions and workers are in fierce competition with the previously untapped talents of other nations. Confronted with these challenges, the question is whether the American educational system is preparing US students in the science, technology, engineering, and mathematics (STEM) fields well enough to preserve the US advantage over other countries that are trying to catch up.
The challenge is twofold. If there is to be a next generation of great US scientists and engineers, the system of science education must inspire students’ interest in STEM and help them reach their potential. The United States cannot count on being able to import the brightest minds of other countries forever. At the same time, US schools have to cultivate scientific literacy and habits of scientific thinking among all students. Americans need to feel comfortable with incorporating scientific concepts in their daily lives for economic reasons, given the growing role of technology in the workplace but also because issues related to science have moved to the center of the nation’s public debate. Discussions about the environment, public health, economic growth, energy, even subjects that are conventionally considered “social” issues are all infused with scientific content. It’s hard to imagine a nation remaining a world leader in science over the long term without a citizenry well informed about science.
US Performance in Science Education
Unfortunately there is a large body of evidence indicating that US students are not learning as much about science as their peers in other countries. Any relative advantage that they enjoyed during the 20th century has disappeared. Even if concerns were limited to the output of scientists and engineers by American universities, there would still be reason to worry. According to a report by the US Congress Joint Economic Committee (2012), although the United States produces more STEM graduates than other industrialized (OECD) nations in terms of raw numbers (no great feat given its much larger population), it ranks 23rd in the percentage of 25- to 34-year-old workers who have a STEM degree.
Demographics among Advanced Degrees
Interest in STEM among postsecondary students appears to be on the wane: whereas in 1985 18 percent of master’s degrees and 24 percent of bachelor’s degrees were in STEM fields, by 2006 those numbers had declined to 14 percent and 18 percent, respectively. The fact that the share of STEM PhDs has remained steady should provide no comfort, as the proportion of American-born STEM PhDs dropped from three-quarters (74 percent) to just over half (54 percent) over a 20-year period. Part of this decline is due to the underrepresentation of disadvantaged minorities among STEM graduates—groups that make up an ever greater share of the US population (Burroughs 2012; also see articles in this issue by Garces and Espinosa and by Malcom-Piqueux and Malcom). Although there is debate about whether there is currently a shortage of STEM graduates (complicated by the unclear effects of the weak economy), the much larger percentage of foreign-born college graduates in STEM than in other fields (Gambino and Gryn 2011; Siebens and Ryan 2012) suggests problems in the US K–12 educational system. This is a particular problem in engineering, where a third of all of those with a bachelor’s or more are nonnative born, twice their share of the US population.
Tests of K–12 Performance
The scientific knowledge of American students starts out fairly strong in early grades relative to children in other countries, but this advantage steadily erodes as they progress. This problem is demonstrated by two assessments of scientific knowledge: the science portions of the US National Assessment of Educational Progress (NAEP)1 and the Trends in International Mathematics and Science Study (TIMSS). The 2009 NAEP indicates that just over a third (34 percent) of US 4th graders are proficient in science, 30 percent in 8th grade, and only 21 percent in 12th grade. In addition, only a vanishingly small 1–2 percent of US students demonstrated an advanced knowledge of science. Although the science NAEP does not at present permit the calculation of long-term trends, a more recent version of the 8th grade NAEP test showed similar results, with a slightly higher 32 percent proficiency.
The 2007 TIMSS2 also makes the point: in 4th grade US students on average scored 539 on the test (ranking 8th among the countries tested), compared with an international average of 500. By 8th grade, they averaged only 520 and were ranked 11th. Since 1995, 4th grade scores have slightly declined (by 3 points) and in 8th grade increased marginally (7 points), although neither of these trends is statistically significant. The US ranking has declined since 1995 for 4th graders, falling from 2nd place, and risen slightly (from 12th) for 8th graders. The TIMSS has a different threshold for its “advanced” level, with 15 percent of 4th graders and 10 percent of 8th graders, numbers that are greater than the international median but that have both declined since 1995 (Gonzales et al. 2009).
The emphasis of the other major international assessment, the Program for International Student Assessment (PISA), is different from that of the TIMSS or NAEP, focusing on the practical application of concepts rather than formal knowledge. The PISA also tests a larger number of countries (both OECD and non-OECD), giving a fuller picture of a country’s relative educational performance. It is noteworthy then that the US performance in science on the 2009 PISA was decidedly mediocre: just 502, compared with the average OECD score of 501 (out of about 800). The United States ranked 17th among 33 OECD countries and 23rd among the 64 participating countries. US performance on the PISA has trended upward since 2006 (up from 489), but its relative ranking did not improve: from a comparative perspective, American students are running in place (Fleischman et al. 2010).
The deteriorating relative position of US students as they proceed through school appears to continue in high school. The 1995 TIMSS3 indicated that by the end of secondary school US students had fallen to 16th of 21 countries in science literacy and well below the international average in physics content areas (Mullis et al. 1998).
Although not our focus here, problematic US mathematics education also impedes the development of a STEM-literate population. As in science, there is a host of evidence from national and international sources that US students are inadequately prepared in mathematics (Schmidt 2012). Only a third of US 4th graders and a quarter of 8th graders reached the level of proficiency on the NAEP; on the TIMSS US students received middling scores, and they did quite poorly on the PISA.
Inequalities in Opportunity to Learn
One of the main obstacles to US science achievement (as with the output of STEM graduates) is the persistence of achievement gaps. All three assessments of US students (PISA, TIMSS, and the NAEP) indicate that low-income and minority students trail their peers by a full standard deviation or more—greater than the half a standard deviation difference between the United States and Singapore on the PISA. Indeed, as laid out in the recent book Inequality for All (Schmidt and McKnight 2012), the US educational system is characterized by pervasive inequalities in opportunity to learn, and such opportunities are strongly related to actual learning (Schmidt and Maier 2009). Students attending low-income schools, whatever their ethnicity, face a particular burden, scoring a full standard deviation and a half below students in affluent schools. In failing to provide educational opportunities to all of its students, the United States is essentially wasting the talents of millions of schoolchildren.
Barriers to Achievement in Science: The Role of Curriculum
After decades in which educational reform policies concentrated on the amount and distribution of educational resources and the structural features of American education, policymakers are now placing an increasing emphasis on the role of instructional content. This new focus is appropriate: what a child has a chance to learn is largely a product of the content to which the student is exposed in the classroom. Although other factors such as socioeconomic background are also important, opportunity to learn has a significant impact on student outcomes—an impact that is the direct result of educational policy. Unlike other nations, the United States has long stood outside the mainstream in its treatment of curriculum, leaving decisions about what students have an opportunity to learn up to state governments or school districts. Unfortunately this has led to a fragmented curriculum and a patchwork of different educational standards, with a dramatic impact on the overall quality of instruction in math and science.
The Need for Focus, Rigor, and Coherence in Curriculum
International research as part of the TIMSS reveals three main features of a strong STEM curriculum: focus, rigor, and coherence (Schmidt et al. 2005). A focused curriculum concentrates on a few key topics at a time, aiming for student mastery. A rigorous curriculum introduces students to these topics at a demanding yet developmentally appropriate level. A coherent curriculum organizes topics in a logical way, moving from the simple to the complex.
Developing a coherent curriculum in mathematics is a much more straightforward task than it is for science. Mathematics is fundamentally a hierarchical discipline, with its own logical structure naturally placing some concepts (e.g., basic arithmetic algorithms) before others (e.g., linear equations and functions). Science, however, is less a single distinct subject than an entire family of content—related to one another, to be sure, but each with its own specific character.
The US science curriculum is “a mile wide and an inch deep,” covering a large number of topics in a scattershot, shallow fashion rather than systematically and in depth. These features are evident both in state and district standards and in textbooks (another important influence on the curriculum). The US science curriculum stands in stark contrast to that of other nations, in particular high-achieving ones such as Japan. Of 79 basic scientific content topics that constitute the TIMSS science framework (Schmidt et al. 1997), US students generally cover more than students in other countries, coverage that tends to be repeated across grade levels without appreciably deepening their knowledge or understanding.
A key question in science is at what grade level a given subject enters the curriculum, since, once included, it tends to remain a part of the curriculum, with a limited increase in depth over time. An examination of the common characteristics of the nations that did best in science on the 1995 TIMSS indicated that higher-performing, or “A+,” countries usually covered little science in grades 1 and 2 (Schmidt et al. 2005). The later primary grades presented basic scientific concepts such as the classification of living organisms, the earth’s features, the nature of matter, and different kinds of energy—topics that serve as the bedrock for physics, biology, and earth science. In early middle school biology topics such as the classification of living organisms and morphology as well as the structure of the solar system and the concept of gravity are introduced. By 7th and 8th grade more advanced topics in chemistry and physics receive attention. In each subfield there is a clear progression from simple description and classification to explanations of change and the underlying processes that govern the physical world.
By comparison, US state standards generally aim to cover many more topics and to do so in every grade, as well as beginning science coverage in the early grades, when they are frequently little more than lists of vocabulary words. An analysis of 44 state standards in 2000 revealed almost no agreement in content coverage across states, and as many as 50 topics to be covered at each grade—far too many for adequate instruction (Schmidt and McKnight 2012). Moreover, a selection of school district standards showed only modest agreement with international benchmarks (39 percent), great variation in content rigor, and little focus.
US science textbooks tend to replicate many of the same flaws as standards, being by international standards very long, very unfocused, and far too elementary. US texts in 4th and 8th grade average 50–65 discrete scientific topics, compared with 5–15 in Japan and 7 in Germany (Cogan and Schmidt 1999; Schmidt et al. 1997). Even textbooks that purport to cover a specific domain of science (e.g., physics) tend to include a large number of topics from other fields. US elementary and middle school textbooks indicate a bias in favor of biology over chemistry and physics, but there is a considerable range in the emphasis given to topics in each of these broader categories.
A further problem in US textbooks is interrupted coverage, as topics are temporarily dropped and later resumed. For example, in 8th grade, US textbooks had between 300 and 600 breaks in topic coverage. The international mean was 88 (Schmidt and McKnight 2012).
Finally, only 20 percent of US 8th grade textbook content involved more complicated information as opposed to simple topics. The typical textbook in other countries devotes about 40 percent of its material to more advanced topics. The danger in a more simplistic approach to science education is that students learn lists of vocabulary words rather than internalizing the scientific approach and learning how to apply it to the world.
Standards and textbooks are examples of the intended curriculum (what students are expected to learn). It is just as important to examine the quality of the implemented curriculum, the content that is actually offered to students in classroom. The key intermediary between intended and implemented curriculum is the science teacher, who has the biggest impact on the content of science instruction. Unfortunately many teachers are not adequately prepared to teach science.
The results of the NCES Schools and Staffing Survey4 indicate that, although 76 percent of high school biology teachers have a major or minor in biology, much smaller proportions of teachers of chemistry (25 percent), earth science (33 percent), physical science (49 percent), or physics (58 percent) have the same level of training. These results are quite similar to those from a survey of teachers in 60 school districts as part of the NSF-funded Promoting Rigorous Outcomes in Mathematics and Science Education (PROMSE) project. That study also surveyed middle school teachers and concluded that those without field-specific training were much less comfortable teaching science topics and that, while 80 percent of high school science teachers had a major or minor in science, only 41 percent of middle school teachers have training in a scientific field. It is hard to expect teachers to implement a strong science curriculum if they are insufficiently prepared.
Adding It All Up
The very problematic quality of teacher preparation, standards, and textbooks contributes to the uneven quality of science instruction, measured according to the choice of topic covered, how many grades, or the time spent on it in a given grade. Studies examining the content of instruction indicate that US topic coverage is far more diffused than in other countries, such as Japan (Schmidt et al. 1999). Even within scientific disciplines, there is very little concentration in the time dedicated to any particular group of topics (Cogan and Schmidt 1999; Schmidt et al. 1997). And again, there is massive variation across school districts and classrooms in the emphasis on given topics. In comparison with the importance placed on physics and chemistry in other nations, in some US classrooms nearly half of the time allocated to science teaching is devoted to these topics and in others they are entirely absent. The difference in the time spent on biology, physics, and chemistry in a given year can range from two to four weeks across classrooms (i.e., class time may be 1 week at one school, 5 weeks at another, and 3 at another).
In sum, the problem of inadequate STEM preparation is linked to the failure to create a coherent science curriculum. The fragmented, incoherent science curriculum—both intended and implemented—poses a potential solution to the puzzle of why American students in elementary and middle school demonstrate a reasonable grasp of scientific knowledge, but have a limited ability to apply these concepts and evince little desire to pursue science as a career.
If scientific topics are littered across classrooms in an almost random fashion, if each scientific subfield is treated as an isolated unit unconnected to the rest, if science is simply a collection of facts offered by teachers who are not always comfortable with them, then can it be any surprise that so many American students fail to take an interest in science?
Improving Focus and Coherence in US Science Instruction
Focus and coherence have always been a challenge in science standards because, as mentioned above, science is not a single discipline. The latest generation of science standards crafted by the National Research Council (NRC 2012; also see Schweingruber et al. 2013 in this issue) made this explicit in its listing of the four disciplinary cores: physical sciences, life sciences, earth and space sciences, and engineering and technology. Note that each of these isn’t a single science but a group of scientific disciplines. The inclusion of numerous subfields to be covered in K–12 science education is likely to increase the already large number of topics and may complicate the effort to fashion a more focused curriculum. An examination of the focus and coherence exhibited in the standards of top achieving countries can provide some guidance, yet such an approach seems to yield little more than a pared down “shopping list” of topics in search of a coherent perspective. How, then, can focus and coherence be brought to the US K–12 science curriculum?
The 8+1 Approach
This was the perplexing challenge facing our NSF-funded project that sought to improve K–12 mathematics and science instruction and learning in over 60 school districts. A group of scientists and science educators5 approached the challenge of focus and coherence by identifying a small number of key concepts that govern the natural world (Schmidt et al. 2011). The idea was that these concepts would cut across the science disciplines and limit the number of essential topics to create a more coherent framework for approaching the whole of science. The result was a set of principles or concepts the group dubbed the “8+1.” In the NRC’s Framework for K–12 Science Education, the “crosscutting concepts” are similarly conceived, in that they are intended to cut across the science disciplinary silos (NRC 2012; Schweingruber et al. 2013). The 8+1 approach attempts to move a step further by responding to three overarching questions:
- How do we know what we know?
- Of what are things made?
- How do systems interact and change?
The answer to the first question, “inquiry,” is the “+1” in the 8+1. Responses to the other two questions about the natural world yield the 8 fundamental concepts of science. In this way the distinguishing feature of science as inquiry is viewed as the means by which one responds to the first overarching question and can formulate responses to the other two.
The following three concepts inform responses to the second question:
- Everything is made of atoms and atoms are composed of subatomic particles.
- Cells are the basic units of organisms.
- Electromagnetic radiation pervades the world.
Responses to the third question yield the final five concepts:
- Evolution: Systems evolve and change with time according to simple underlying rules or laws.
- Parts of a system move and interact with each other through forces.
- Parts of a system can exchange energy and matter when they interact.
- Physical concepts like energy and mass can be stored and transformed, but are never created or destroyed.
- Life systems evolve through variation.
These concepts6 were developed not as a new set of standards but as a set of fundamental principles that support and provide connection among the many different topics included in science standards. The goal in creating the 8+1 framework is to support whatever standards are the focus of classroom instruction as well as whatever textbooks or materials are in use, to go beyond the facts and connect them to the 8+1 fundamental concepts. In addition, the concept of system is an important idea that moves science instruction away from a consideration of isolated facts (and vocabulary) and instead emphasizes the dynamic relationships among system elements.
The vision is to have the 8+1 serve as the foundation that supports and informs instruction and the effort to help students make sense of the natural world. Coherence, then, emerges in the science curriculum not only through the sequence in which topics are covered but, more importantly, in the many connections that can be made explicit among them through the 8+1. These fundamental concepts are always relevant in that many (if not most) of them undergird whatever topic may be taught.
Cultivating the Next Generation of US Innovators
In creating a framework that helps students synthesize across scientific subfields, the 8+1 has the potential to foster greater science literacy. As understood by physicist and Nobel Laureate Leon Lederman, one of the authors of 8+1, students need to comprehend both what science is and what it is for. According to Lederman:
Science is able to explain the way the natural world works by means of a small number of laws of nature. These laws, often expressed mathematically, are explored using tools such as observation, measurement, and description. Information is synthesized into understanding through creative thought with predictions continuously tested by observation and measurement. (Schmidt et al. 2011, p. 7)
Engineering could play a useful role in realizing the 8+1. It is not a separate science discipline but rather the application of scientific concepts and principles to solve specific problems. Structuring science instruction around the 8+1 provides a way to bring engineering into the classroom on a regular basis. Both the practice of engineering and the conceptual foundation of the 8+1 embrace the multidisciplinary nature of science and make explicit use of the interconnections. These linkages, brought together in a practical solution or linked to fundamental crosscutting concepts, can bring much-needed coherence to science instruction by making science a compelling reality for students.
The fundamental science concepts embodied in 8+1 are not a miracle cure for what ails science learning, but they do suggest a compelling approach to improved science instruction in the classroom that merits exploration. Assuming that a fragmented, mile-wide inch-deep science curriculum is a major contributor to mediocre science literacy and a lack of interest in STEM careers, the 8+1, together with improved preparation of teachers of science and an aggressive effort to reduce the inequality in opportunity to learn science, presents a promising strategy for fostering the next generation of American innovators.
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1 Data collected from the NAEP data explorer, http://nces.ed.gov/nationsreportcard/naepdata/.
2 These are the most recent data available as the TIMSS is conducted every 5 years.
3 TIMSS conducted a study of secondary school students only in 1995, but given the stable performance of US students at other grades and in other assessments, these results very likely hold true in 2013.
4 Available online at http://nces.ed.gov/surveys/sass/tables/sass0708_009_t1n.asp.
5 The group members were Simon Billinge, Audrey Champagne, Richard Hake, Paula Heron, Leon Lederman, George Leroi, Lillian McDermott, Fred Myers, Roland Otto, Jay Pasachoff, Carl Pennypacker, William Schmidt, and Paul Williams.
6 For more information about the concepts and their age-appropriate definitions, see http://8plus1science.org/.