A new Pew Research Center survey finds that most Americans can answer basic questions about several scientific terms and concepts, such as the layers of the Earth and the elements needed to make nuclear energy. But other science-related terms and applications, such as what property of a sound wave determines loudness and the effect of higher altitudes on cooking time, are not as well understood.

Most Americans (86%) correctly identify the Earth’s inner layer, the core, as its hottest part, and nearly as many (82%) know uranium is needed to make nuclear energy and nuclear weapons.

But far fewer are able to identify the property of a sound wave that determines loudness. Just 35% correctly answer amplitude, or height. Some 33% incorrectly say it is frequency and 23% say it is wavelength. And just 34% correctly state that water boils at a lower temperature in a high-altitude setting (Denver) than near sea level (Los Angeles).

Fully 73% of Americans distinguish between astronomy and what is commonly considered a pseudoscience: astrology. Twenty-two percent of Americans incorrectly say that astronomy – not astrology – is the study of how the positions of stars and planets can influence human behavior. Another 5% give some other incorrect response.

How much Americans appear to know about science depends on the kinds of questions asked, of course. Science encompasses a vast array of fields and information, and the questions in the new Pew Research survey represent a small slice of science knowledge. On Pew Research Center’s set of 12 multiple-choice questions – some of which include images as part of the questions or answer options – Americans gave more correct than incorrect answers; the median was eight correct answers out of 12 (mean 7.9). Some 27% answered eight or nine questions correctly, while another 26% answered 10 or 11 items correctly. Just 6% of respondents got a perfect score.

These findings come from Pew Research Center’s American Trends Panel, a nationally representative panel of randomly selected U.S. adults. The survey of 3,278 adults (including 2,923 adults online and 355 respondents by mail) was conducted Aug. 11-Sept. 3, 2014.

Why science knowledge matters

A variety of scholars have argued that public understanding of science issues and concepts is a hallmark of an informed public.¹ As developments in science and technology raise new issues for public debate – from driverless cars and space exploration to climate change and genetically modified crops – a public with more knowledge of scientific facts and principles is often seen as one better able to understand these developments and make informed judgments.²

One major avenue for science learning is through the schools. But neither the public nor those connected to science have strongly positive views about America’s science and technology education. A 2015 Pew Research report found that the general population and members of the American Association for the Advancement of Science (AAAS) both see U.S. K-12 education in science, technology, engineering and mathematics (STEM) fields as “average” or “below average” compared with other industrialized countries.

A minority of 29% of Americans and 16% among AAAS members consider the country’s K-12 STEM education to be among the best in the world.

Moreover, 84% of AAAS members consider Americans’ limited knowledge about science to be a major problem for the scientific enterprise. Further, most of the AAAS members say that too little STEM education is a major reason that the public has limited science knowledge.

Those with higher education levels are more likely to know answers to questions about science. There are also times when gender, age, race and ethnicity matter.

There are substantial differences among Americans when it comes to knowledge and understanding of science topics. In the new survey, education proves to be a major factor distinguishing higher performers on our science questions from those who get fewer correct. Adults with postgraduate and college degrees performed better than those with a high school diploma or less. This pattern is consistent with a 2013 Pew Research report on this topic.

Pew Research’s findings are also consistent with analysis of the factual knowledge index in the National Science Board’s Science and Engineering Indicators. That research finds that higher educational levels are associated with more factual knowledge of science, and that college graduates who took at least three college-level courses in science or mathematics have higher levels of science knowledge than do those who took fewer science and math courses.³

The new Pew Research survey also finds gaps in science knowledge between men and women, with men outperforming women on many questions – even when comparing men and women with similar levels of education.

Questions on this survey deal primarily with topics tied to the physical sciences, rather than life sciences such as those related to health and medicine. Research by the federal government has found that gender differences in science knowledge tend to be larger on questions about the physical sciences than the life sciences.⁴

In previous Pew Research surveys that are also detailed in this report, there were no differences or only modest knowledge differences between men and women on four health and biomedical topics in the news. For instance, on one previous question, women were more likely than men to answer correctly that antibiotics do not kill both viruses and bacteria. At the same time, men were more likely than women to know that the main function of red blood cells is to carry oxygen throughout the body. The Science and Engineering Indicators report found no difference between adult men and women on factual knowledge of biomedical topics.⁵

Generally, younger adults display slightly higher overall knowledge of science than adults ages 65 and older on the 12 questions in the new Pew Research survey. On some questions, younger adults are particularly well-informed. For example, 80% of adults ages 18 to 29 correctly identify radio waves as the waves that are used to transmit cellphone calls, as do 77% of those ages 30 to 49; fewer adults (57%) ages 65 and older know this. On at least one question, however, adults ages 65 and older are more informed than younger adults: 86% of adults 65 and older correctly identify the developer of the polio vaccine as Jonas Salk, compared with 68% of those ages 18 to 29.

There are also differences associated with race and ethnicity in the new survey’s 12 questions. Whites are more likely than Hispanics or blacks to answer more of these questions correctly, on average; the mean number of items correct is 8.4 for whites, 7.1 for Hispanics and 5.9 for blacks. The pattern across these groups and the size of the differences vary, however.

The findings on race and ethnicity are broadly consistent with results on science knowledge questions in the General Social Surveys between 2006 and 2014. Pew Research analysis of the GSS data finds white adults scored an average of 6.1 out of 9 questions correctly, compared with 4.8 for Hispanics and 4.3 for blacks. While whites, blacks and Hispanics with higher education levels know more factual science items on average, mean differences by race and ethnicity occur among all education levels.⁶ As with gender differences, differences by race and ethnicity could tie to a number of factors, including differences in areas of study at the high school, college and postgraduate levels and other factors.⁷ To the extent that science knowledge, especially on issues in the news and emerging scientific developments, is learned in connection with adult life activities, the long-standing underrepresentation of blacks and Hispanics in the science, technology, engineering and mathematics workforce could also be a contributing factor.⁸

The questions in the new Pew Research Center survey represent only a small slice of science knowledge. Science encompasses a vast array of fields and information. Across the set of 12 science knowledge questions in this survey, it is clear that some information is widely known while other information is much less so. To allow for comparisons across a wider array of questions and topics, we include a series of tables in this report with findings from the new Pew Research survey and from previous Pew Research studies. Comparisons across surveys should be made cautiously. The new survey includes several questions with images or photographs displayed online or in a print questionnaire. Past surveys were, with one exception, conducted by telephone and thus relied solely on respondents’ aural and verbal skills. Little is known about how different modes of interview could influence the findings. Nonetheless, these comparisons help illustrate that the broad patterns of differences in science knowledge by education and demographic subgroups in this new survey are generally in keeping with previous Pew Research surveys that tapped public knowledge about science.

Among the science questions in the new Pew Research Center survey that were easiest for most to answer correctly: 86% identify the Earth’s inner layer, called the core, as its hottest part.⁹ A nearly equal share, 82%, knows that uranium is needed to make nuclear energy and nuclear weapons.

In addition, 78% of Americans correctly identify a comet when looking at a photograph described as having an icy core with a tail of gas and dust that extends millions of miles. And 72% of Americans know that radio waves, not sound waves, are used to make and receive cellphone calls. The same share of the public (72%) also knows that a light-year measures distance, not time. Elaboration on our question language: In designing the question about cellphones, we tried to use language that would be commonly understood among the non-expert public. Several readers and quiz-takers wrote to suggest that one of the response options we offered would be better expressed as “visible light waves” rather than the way we listed it, “light waves.” They noted that radio waves are also on the electromagnetic spectrum that includes both radio waves and light waves. Our question used the phrase to “send and receive cellphone calls” to try to convey to those being asked the question that we were referring to the waves needed to transmit calls between cellphone towers, not just the sound involved in talking with someone by telephone. Just 3% selected “light waves” in our national survey and some 72% of the general public responded that radio waves are needed to make and receive cellphone calls, an explanation that is consistent with explainers for the general public by the Institute for Physics.

Some 76% know that ocean tides are created by the moon’s gravitational pull. (But just 5% know that tides are affected not just by the moon but by the gravitational pull of the sun and the rotation of the Earth as well.)

Americans fare well as a whole when it comes to one aspect of science history: Fully 74% of Americans correctly identify Jonas Salk as the person who developed the polio vaccine from among a list of other scientists that included Marie Curie, Albert Einstein and Isaac Newton.

Most Americans can distinguish between astronomy and astrology. Seventy-three percent of adults recognize the definition of astrology as the study of how the position of the stars and planets can influence human behavior. By comparison, 22% of adults incorrectly associate this definition with astronomy, while another 5% give some other incorrect response.

Some 63% Americans correctly say that the findings

from a scatterplot chart show the average number of decayed teeth per person in different countries, plotted along with average sugar consumption per person, per day.¹⁰

But several questions prove more difficult for a majority of U.S. adults.

Survey respondents have comparatively more trouble identifying, from a set of four images, how light passes through a magnifying glass; 46% identify the correct image showing the lines crossing after they pass through a magnifying glass. More than half of the public (54%) choose an incorrect option, including 34% who incorrectly identify the image showing the lines moving outward from each other after passing through the glass.¹¹

Even fewer Americans are able to identify what property of a sound wave determines the loudness of sound. In all, 35% correctly answer the amplitude, or height, of the wave.

And most Americans are unclear how altitude affects the boiling temperature of water. When asked to consider Denver (at a high elevation) and Los Angeles (near sea level), and whether the boiling temperature of water would change at the higher elevation, 34% correctly answer that water boils at a lower temperature in Denver than in Los Angeles. (For more background on this topic see “Does waters boiling point change with altitude? Americans aren’t sure.”)

In the new Pew Research Center survey, more-educated Americans generally score better overall in answering science-related questions than those who have a high school degree or less. And those with a college degree or higher tend to perform better on the toughest questions.

Adults with a college or postgraduate degree are more than twice as likely to get at least eight out of 12 questions right, compared with adults with a high school diploma or less (82% vs. 40%). Those with a postgraduate degree score an average of 9.5 correct answers out of 12, while those with a high school education or less get an average of 6.8 correct.

Fully 57% of adults with a postgraduate degree get 10 to 12 correct answers, whereas this is true for 18% of those with a high school diploma or less.

On all 12 questions, there is at least a 13 percentage point difference in correct answers between the highest- and lowest-educated groups. The largest difference is found in a question about the loudness of a sound. A 62% majority of those with a postgraduate degree correctly identify the amplitude (height) of the sound wave as determining its loudness, as do 52% of those with a four-year college degree. By contrast, 20% of those with a high school education or less answer this question correctly. And there is a 34-point gap between these groups in correctly interpreting a scatterplot chart from among a list of four options. Half (50%) of those with a high school diploma or less answer this question correctly, compared with 84% among those who completed a postgraduate degree.

Differences by education in science knowledge were also found in previous Pew Research surveys on this topic, as detailed in a later section. These findings are also consistent with analysis of the factual science knowledge index in the National Science Board’s Science and Engineering Indicators. That research finds higher education levels associated with more factual knowledge of science. College graduates who took at least three college-level courses in science or mathematics have higher levels of knowledge about science than do those who took fewer science and math courses.¹²

Men tend to answer more of these science knowledge questions correctly than do women, the new Pew Research Center survey found. Men score an average of 8.6 out of 12 correct answers, compared with women’s 7.3 correct answers.

Some 24% of women answer 10 or more questions correctly, compared with 43% of men who did this. And 69% of men get at least eight of the questions right, compared with 51% of women.

The largest difference between men and women occurs on a question asking respondents to select from a set of four images that illustrate what happens to light when it passes through a magnifying glass. Some 55% of men and 37% of women identify the correct image showing the lines crossing after they pass through a magnifying glass, a difference of 18 percentage points. There was also a 15-point difference between the sexes on knowledge about one topic commonly discussed in world news and foreign policy: While three-quarters of women (75%) correctly identify uranium as an element needed to make nuclear energy and nuclear weapons, nine-in-ten men answer this correctly.

Men (73%) and women (72%) are equally likely to identify the definition of astrology from a set of four options, however. And on the question about which layer of the Earth is hottest, there are only modest differences, with 89% of men and 84% of women selecting the correct response.

Education differences between men and women, particularly among older generations of adults, may explain some of these gendered patterns in science knowledge. For example, men and women who hold a postgraduate degree are about equally likely to correctly interpret a scatterplot chart and to know that ocean tides are influenced by the gravitational pull of the moon. But, on average, men tend to know more of the answers to these science questions than do women, even when controlling for each of four levels of education.

According to government research on issues of science knowledge, males and females tend to differ in their expressed interest in science topics and in their course selection at the high school, college and postgraduate levels. Men, on average, express greater interest in the physical sciences than women. This could in part explain the tendency for men to know the right answers to more of these questions, which focus mostly on the physical sciences, than women, even when controlling for educational level.¹³ The U.S. government’s Science and Engineering Indicators 2014 report shows that women and men tend to score about equally high on factual knowledge items in the biological sciences, while men tend to score higher on scales of factual knowledge in the physical sciences.¹⁴

Pew Research Center surveys have included only a handful of biological science knowledge questions over the years. As detailed in a later section, on four questions related to health and biomedical issues in the news, there were no differences or only modest differences between men and women. And, on two other questions that tie more closely to the kinds of knowledge taught in school, women (59%) were more likely than men (49%) to know that antibiotics will not kill viruses, according to a 2009 Pew Research survey. However, a 2014 Pew Research survey found men (80%) more likely than women (73%) to correctly identify the main function of red blood cells.

In addition, the questions on the Pew Research survey ask for knowledge or applications of scientific principles, such as the definition of a light-year or the principles underlying sound, rather than questions designed to measure understanding of scientific processes or methods used to test scientific theories. The Science and Engineering Indicators report found no difference between adult men and women on measures designed to tap understanding of probabilities, experiments, or a basic understanding of the scientific method.¹⁵ Previous Pew Research surveys have included only one question measuring understanding of scientific processes. On that question, women (78%) were slightly more likely than men (72%) to identify comparison groups as a better way to study the effectiveness of a drug treatment than a single treatment group.

People’s science knowledge sometimes varies by age, race and ethnicity, though the patterns are far from uniform across this set of 12 questions in the new Pew Research survey. On some questions, younger adults tend to know more than their elders (such as which kind of waves underlie cellphone calls). But that pattern is reversed when it comes to awareness that Jonas Salk developed the polio vaccine. Differences by race and ethnicity also vary across the set, with whites answering more of these questions correctly on average than Hispanics or blacks.

Generations and Knowledge

There are notable age gaps in knowledge about some science topics. Fully eight-in-ten (80%) adults ages 18 to 29 correctly identify radio waves as the technology underlying cellphone calls. By contrast, 57% of those ages 65 and older know this.

On some questions there are no differences in knowledge across age groups. For example, both younger and older adults are about equally likely to identify a given definition as that of astrology from a list of other choices, including astronomy.

And, when it comes to one aspect of science history, older adults (ages 65 and older) are more likely than younger adults to identify Jonas Salk as the person who developed the polio vaccine when given a list of scientists that also includes Marie Curie, Albert Einstein and Isaac Newton. Fully 86% of those ages 65 and older correctly identify Salk as the vaccine’s developer, compared with 68% of adults ages 18 to 29.

Overall, differences by age across this set of questions are generally modest. The oldest adults – ages 65 and up – score lower, on average 7.6 out of 12 items, compared with younger age groups (ages 18 to 49). But adults under age 30 and those ages 30 to 49 tend to identify a similar mean number of items correctly.

Race and Ethnicity

There are also differences by race and ethnicity across these items, on average, with whites knowing the correct answer to more of these questions overall than Hispanics or blacks. Whites score a mean of 8.4 items out of 12 correct, compared with 7.1 among Hispanics and 5.9 among blacks.¹⁶

One of the largest differences between blacks and whites occurs on a question about the ocean tides: 83% of whites compared with 46% of blacks correctly identify the gravitational pull of the moon as one factor in ocean tides. (Hispanics fall in between these two groups, with 70% answering this question correctly.) On one of the more difficult questions, a roughly equal share of whites (36%) and blacks (33%) correctly identify a difference found in cooking at higher altitudes: that water boils at a lower temperature. A quarter (25%) of Hispanics answered this question correctly.

Educational differences across race and ethnic groups may contribute to science knowledge differences among whites, blacks and Hispanics. But whites tend to score higher, on average, on this set of science knowledge questions than do either Hispanics or blacks, even after controlling for education. Such comparisons need to be made cautiously due to the smaller number of respondents in this survey who are African-American (n=259) or Hispanic (n=247). The sample size of these subgroups does not allow for detailed comparisons by education level.

Science knowledge differences by race and ethnicity have also been found in other surveys. As detailed in a later section, previous Pew Research surveys have also found knowledge differences by race and ethnicity on a range of science topics. On the factual science knowledge questions collected on the General Social Survey (GSS) between 2006 and 2014, for example, whites scored an average of 6.1 out of 9 questions correctly, compared with 4.3 for blacks and 4.8 for Hispanics. Racial and ethnic group differences in mean numbers of correct responses on that scale occur even when controlling for education level.¹⁷

Differences by race and ethnicity could tie to a number of factors, including long-standing disparities among race and ethnic groups on science achievement tests; differences in areas of study at the high school, college and postgraduate levels; and other factors.¹⁸ To the extent that science knowledge, especially on issues in the news and emerging scientific developments, is learned in connection with adult life activities, the continued underrepresentation of racial and ethnic minority groups in science, technology, engineering and mathematics workforce could also be a contributing factor.¹⁹ (For more on this see topic see “The race gap in science knowledge.”)

The set of 12 questions from the new Pew Research Center survey is, of course, only a small fraction of the possible topics and approaches to measuring public knowledge and understanding about science. In this section, we show the 12 questions from the new survey alongside other science knowledge questions asked across a handful of past Pew Research surveys conducted since 2009. This overview of findings underscores the caution that how much the public appears to know or not know about science depends on the nature of the questions asked. Some information is widely held, other information much less so. It also shows that the broad patterns described above of differences in science knowledge by educational level and across demographic groups tend to be consistent with the patterns found in earlier surveys that used different science knowledge questions and different survey methods.

People who happen to know more, on average, about the particular questions on a given survey are expected to know more about other topics within the broad domain of science. But there may be differences depending on the fields of science covered, as well as the extent to which the questions tap information that may be learned from developments in the news or applications of scientific principles in everyday life. Thus, the tables here show the questions grouped into broad topical categories related to the life sciences, earth sciences and energy issues, as well as other physical sciences. The questions are also grouped into broad types, such as those that might come from news coverage of science and technology issues or applications of science in everyday life and those that might be found in science education textbooks.

Knowledge of science facts, especially those typically covered in science textbooks, tends to be stable over time. For example, the average number of items correct on a nine-item scale of factual knowledge of science collected on behalf of the National Center of Science and Engineering Statistics has stayed about same the over the past two decades.²⁰ Topics connected with emerging science and science-related issues covered in the news may be more likely to change over time.

The new Pew Research survey findings were collected primarily online with a nationally representative sample of adults (in the center’s American Trends Panel), so the large majority of respondents completed the survey using a computer or smartphone.²¹ Most of the past Pew Research surveys with science knowledge questions were conducted by telephone, however. Little is known about how different modes of data collection might influence estimates of science knowledge. Prior to fielding the new science knowledge survey online, we did one mode experiment in which half the respondents from the American Trends Panel were randomly assigned to answer an item about the most common source of electricity in the U.S. via a phone survey, and the other half were presented the question online. There were no significant differences in knowledge across the two modes. For more on mode differences, see the Pew Research report “From Telephone to the Web: The Challenge of Mode of Interview Effects in Public Opinion Polls.”

Readers should also keep in mind that the estimates of public knowledge about science may vary depending on the extent to which respondents are encouraged to guess. Respondents in these surveys were instructed to provide their best guess, even if they were not certain of the correct answer, and while they were able to skip questions, there was no explicit option to say “don’t know.” One recent analysis of science knowledge questions collected on the General Social Survey suggests that instructions that discourage guessing (e.g., by making it easier to record a don’t know response) may provide a more valid measure of science understanding because some of those who guess will provide the correct response by chance without holding a clear understanding of the scientific principles.²²

However, some studies of adult knowledge in the political domain have argued that surveys that discourage guessing by offering an explicit “don’t know” option underestimate knowledge because some respondents have meaningful, though partial, information but are less inclined to guess in those situations.²³ One recent study of political knowledge argues that visual cues tap into different stores of political knowledge than do questions based only on verbal cues, and that educated respondents may have more of an advantage on verbal than visual knowledge questions. ²⁴

These issues go beyond what we can disentangle here. Despite the limitations of any survey, Pew Research Center’s science knowledge findings provide a nationally representative snapshot of what the public knows on new and older scientific developments, textbook principles covered in K-12 education, and topics discussed in the news. The overall findings and the divides among key demographic groups provides a fresh look at the American public’s science knowledge and may provide new insights for the larger civic effort on science education among both children and adults.

This report examines the general public’s knowledge about 12 science-related topics. The data were collected on the Pew Research Center’s American Trends Panel. This report also includes a series of tables with findings from the new Pew Research survey and from previous Pew Research studies on science knowledge to allow for comparisons across a wider array of questions and topics.

This report is a collaborative effort based on the input and analysis of the following individuals. Find related reports online at pewresearch.org/pewresearch-org/science2015.

Cary Funk, Associate Director, Research Sara Kehaulani Goo, Senior Digital Editor Brian Kennedy, Research Associate Lee Rainie, Director Internet, Science, and Technology Research Monica Anderson, Research Analyst Kenneth Olmstead, Research Associate Andrew Perrin, Research Assistant Dana Page, Senior Communications Manager David Kent, Copy Editor Margaret Porteus, Information Graphics Designer Shannon Greenwood, Assistant Digital Producer Scott Keeter, Director, Survey Research Kyley McGeeney, Research Methodologist Ruth Igielnik, Research Associate Andrew Mercer, Research Methodologist

The American Trends Panel (ATP), created by Pew Research Center, is a nationally representative panel of randomly selected U.S. adults living in households. Respondents who self-identify as internet users (representing 89% of U.S. adults) participate in the panel via monthly self-administered Web surveys, and those who do not use the internet participate via telephone or mail. The panel is being managed by Abt SRBI.

Data in this report are drawn from the August wave of the panel, conducted Aug. 11-Sept. 3, 2014, among 3,278 respondents (2,923 by Web and 355 by mail). The margin of sampling error for the full sample of 3,278 respondents is plus or minus 2.3 percentage points.

All current members of the American Trends Panel were originally recruited from the 2014 Political Polarization and Typology Survey, a large (n=10,013) national landline and cellphone random digit dial (RDD) survey conducted Jan. 23 to March 16, 2014, in English and Spanish. At the end of that survey, respondents were invited to join the panel. The invitation was extended to all respondents who use the internet (from any location) and a random subsample of respondents who do not use the internet.²⁵

Of the 10,013 adults interviewed, 9,809 were invited to take part in the panel. A total of 5,338 agreed to participate and provided either a mailing address or an email address to which a welcome packet, a monetary incentive and future survey invitations could be sent. Panelists also receive a small monetary incentive after participating in each wave of the survey.

The ATP data were weighted in a multi-step process that begins with a base weight incorporating the respondents’ original survey selection probability and the fact that some panelists were subsampled for invitation to the panel. Next, an adjustment was made for the fact that the propensity to join the panel varied across different groups in the sample. The final step in the weighting uses an iterative technique that matches gender, age, education, race, Hispanic origin and region to parameters from the U.S. Census Bureau’s 2012 American Community Survey. Population density is weighted to match the 2010 U.S. Decennial Census. Telephone service is weighted to estimates of telephone coverage for 2014 that were projected from the July-December 2013 National Health Interview Survey. It also adjusts for party affiliation using an average of the three most recent Pew Research Center general public telephone surveys, and for internet use using as a parameter a measure from the 2014 Survey of Political Polarization. Sampling errors and statistical tests of significance take into account the effect of weighting. The Hispanic sample in the American Trends Panel is predominantly native born and English speaking.

The following table shows the unweighted sample sizes and the error attributable to sampling that would be expected at the 95% level of confidence for different groups in the survey:

Sample sizes and sampling errors for other subgroups are available upon request.

In addition to sampling error, one should bear in mind that question wording and practical difficulties in conducting surveys can introduce error or bias into the findings of opinion polls.

The Web component of the August wave had a response rate of 62% (2,923 responses among 4,702 Web-based individuals enrolled in the panel); the mail component had a response rate of 64% (355 responses among 559 non-Web individuals enrolled in the panel). Taking account of the response rate for the 2014 Survey of Political Polarization (10.6%), the cumulative response rate for the August ATP wave is 3.6%.