If the 20th century was the century of physics, the 21st century has been touted as the century of biology (Venter & Cohen, 2004). It has been over 60 years since the molecular structure and the biological function of deoxyribonucleic acid (DNA) was discovered. Since then, understanding of DNA has driven enormous growth in genetics and biomedical science. Biology is underpinned by the coding and transmission of life’s information by DNA at the molecular level, and the evolution of organisms by natural selection at the species level. A case can be made that understanding DNA is as foundational for science literacy as understanding Darwin’s theory of evolution.

Biology is taught to almost every student in the United States during their K–12 schooling: 96% of students in the United States take basic biology at the secondary levels (Kena et al., 2015). DNA is the molecule at the heart of coding function and form in living organisms. Understanding DNA and concepts associated with it (e.g., genetic information, heredity) is necessary to understand media reports of biology, make health-care decisions, and to understand the spread and treatment of diseases in the world. An understanding of DNA is not only central to science education, but also for informed participation of college-educated adults in popular culture, modern health, and hygiene. Additionally, for college students in life-science majors, understanding DNA is crucial for them to build more complex understandings relevant to their coursework and future careers. Biology is the focus of this work because it constitutes a large and growing segment of the science, technology, engineering, or mathematics (STEM) major population. Biology also features prominently in societal debates over evolution, genetic engineering, and gene therapy in medicine. Ideally, we want the public to gain a well-rounded, accurate idea of how biology impacts our world, and ensuring this requires effective instruction for both science and nonscience majors.

In this study, we compared the knowledge of general-education students, both STEM and non-STEM majors, to students who were enrolled in a required introductory biology course for life-science majors at the same institution. The goal was to compare the biological and general science knowledge of our general-education students to that of students who had selected a biology-related major and were working toward careers in the life sciences. We additionally wanted to compare the science knowledge of students attending college compared to the general public. Overall, we were interested in whether students who were on paths to become future scientists and health-care professionals had greater scientific knowledge than the future lawyers, artists, and government officials (and others) in our non-STEM cohort. We also hoped to understand the topics students are struggling to understand, to be able to adapt science courses for both groups to focus on the areas of greatest difficulty.

Background and context

We have been investigating students’ knowledge and attitudes about science, and our prior work has examined undergraduate students’ knowledge of basic science facts, beliefs in nonscientific phenomena (including astrology), and how students describe what it means to study something scientifically (Impey et al., 2011; Impey et al., 2012). We have collected data since 1989 from over 12,000 students enrolled in introductory astronomy courses, often used to fulfill a general education requirement. These students (henceforth called GenEd students) are primarily early-career college students who have completed from zero to the required two college-level science classes. The great majority of the students are nonscience majors. As documented elsewhere (Impey et al., 2011), these students are representative of the general (college-educated) public. The sample is approximately gender balanced. Our previous analyses have shown that these students outperform the general public on basic science questions, as measured by a survey administered by the National Science Foundation (NSF) and published in the biennial Science and Engineering Indicators (NSB, 2014). We have seen no overall change in students’ science knowledge over the 27 years of the survey, with a consistent average score of around 75% each year (Impey et al., 2012). Students who self-reported as STEM majors outperformed non-STEM majors in terms of science knowledge by only 5%. Based on these findings, we decided to take a closer look at STEM and non-STEM majors in the GenEd course and compare their answers to science majors taking an introductory biology course.

Methods

This study was conducted during the 2013–2014 academic year. We have collected data from our GenEd population since 1989, but started data collection from the students taking an introductory-biology course in 2013. Thus, we restricted our GenEd survey data for this study to that same year. We collected data from a total 397 GenEd students and 187 early-biology students. The survey includes both forced-choice and open-ended items in both physical and biological science (see Online Supplemental Materials). Physical science questions test basic facts such as knowing that light travels faster than sound and recognizing that the Earth goes around the Sun. Biological science questions test the knowledge that viruses cannot be killed by antibiotics, that humans and dinosaurs did not coexist, and that the inheritance of some diseases is governed by probability.

Early-biology students were students who committed to major in the life-sciences and were taking their first biology class in the Molecular and Cellular Biology Department at the University. This course highlighted DNA’s physical and chemical properties as well as its role in cells. The early-biology student sample represented future scientists, health-care practitioners, engineers, and chemists; we hypothesized that they would outperform students who were on a trajectory toward nonscientific professions.

To further test our prediction, we gathered additional data from a biological-research group at our university who assessed students with a survey containing overlapping questions with our survey. These students were selected to work in biology labs through the Undergraduate Biology Research Program (henceforth called advanced-biology students). To study the spectrum of students’ knowledge, we looked at similar questions answered by our GenEd students broken down by STEM and non-STEM majors, by early-biology students beginning their college career, and by advanced-biology students working in research labs between their second and final years in college. Because our questions overlapped with those used in a survey of the general public conducted by the National Science Board and published by the NSF in the Science and Engineering Indicators series (NSB, 2014), we were also able to compare the student responses to those of the general public.

For the analysis, GenEd students were separated into two main categories corresponding to students’ self-reported majors: those who had declared a major in the STEM majors and those who had not (non-STEM majors). All the early-biology students in the study were self-reported STEM majors.

The advanced-biology students participated in a highly selective research experience. These students had already completed their introductory science courses and all of whom were self-reported STEM majors. Data were collected from 127 students as part of an ongoing program evaluation of the research experience.

Finally, the NSF has commissioned a biannual survey of the general public since 1993 that addresses the public’s attitudes toward, and their perceptions of, science and society. These data are made publicly available for analysis. We used all the data (n = 2,256) but broke down results by individuals who did not go to college, those who had some college (most comparable to our sample), and those who had a college or post-Bachelor’s degree. Respondents answered questions during 2012, which were then published in the Science and Engineering Indicators 2014 report (NSB, 2014).

Participants

Most of the GenEd students were in their first two years of college (Table 1), and the majority had taken one or no college science classes (Table 2). Ten percent of the GenEd students reported being a STEM major, typically engineering, physics, biology, chemistry, and health science. Four students in the GenEd astronomy class were biology majors. The non-STEM majors included a large proportion of business or social and behavioral science (Table 3). In terms of gender, 57% of the GenEd students were male and 43% were female.

Most early-biology students were in their first two years of college. Over half (53%) had taken four or more college science classes before the introductory biology class, 27% took two or three science classes, and for 19% this introductory-biology course was their first or second science class in college (Table 2). The majority of the introductory biology students were majoring in health sciences (further breakdown of the majors is included in Table 3).

Most of the advanced-biology students were juniors or seniors in college (82%) and none were freshman. Almost all had taken four or more college science courses. These students were mostly life-science majors, including molecular and cellular biology, biochemistry, general biology, chemistry, bioengineering, and evolutionary biology majors. The rest majored in speech, psychology, engineering and other non-life-science majors.

Analysis

The initial analysis of students’ survey responses included open-ended descriptions of DNA and descriptive statistics of the science knowledge scores. Analysis for the DNA free-response item (see Q13 in the Online Supplemental Materials) was based on our coding scheme for this question (Impey et al., 2012). The codebook originally derived was revised in collaboration with the instructor of the early-biology students’ course, an experienced biologist and science educator. Initial coding involved reading responses and binning it based on the categories in the codebook. For example, a statement stating DNA is “from your parents,” would be coded for heredity. Each response was read by 3 coders and intercompared. Each of the codes was grouped into a larger theme: incorrect ideas about DNA, physical characteristics of DNA, chemical characteristics of DNA, location of DNA in the cell, functions of DNA, how DNA is used in real-life situations, metaphors to describe DNA, and media references and trivial descriptions of DNA. To further our analysis, we looked for trends between students who mentioned specific DNA themes and popular phrases and their science knowledge scores or demographics. Finally, we compared the coded responses of the GenEd students and the early-biology students. The coding scheme was applied consistently across the different student groups.

To quantify students’ basic knowledge, we created a biological science–knowledge score and an overall science-knowledge score based on the forced-choice, science-knowledge items on the survey (see Online Supplemental Materials). The biological science–knowledge score included the nine life-science questions from the survey and was scored out of nine points (see Q3, Q8 and 9, Q16, Q17, and Q19A–D in the Online Supplemental Materials). The overall science-knowledge score included all the force-choice items answered and had a maximum score of 17 points.

Results

The GenEd students had an average science-knowledge score of 13.7 points out of 17 (81%) and an average biological science–knowledge score of 7.1 out of 9 (79%) points (Table 4). Although the STEM majors in the GenEd class scored slightly higher than the non-STEM majors, these differences were not statistically significant, (t = 1.76 p > .05; t = 1.31, p > .05). The STEM majors had an average science-knowledge score of 14.4 points (84%), and an average biological science–knowledge score of 7.4 points (83%). Among the GenEd students, science majors had the highest scores and education majors had the lowest scores for both science-knowledge measures.

The early-biology students had an average overall science score of 14.4 points (85%) and a biological science score of 7.6 points (84%). The GenEd STEM students and the early-biology students had statistically indistinguishable scores (p > .05). This suggests that students on a STEM major path enter college having learned the same information in high school and in other nonschool settings prior to college.

Additionally, we compared the GenEd and early-biology students to both the advanced-biology students and the general public (NSF sample) for three of the five biological questions that overlapped on all four surveys. These three true/false items are questions 8, 16, and 17 in the Online Supplemental Materials. This was to assess the difference in biology knowledge between students who chose to go to college, students who chose a STEM major, and the general public (separated into those who did not go to college, those who had some college, and those who had a Bachelor’s or more advanced degree).

Figure 1 shows that the advanced-biology students outperformed every other group on the question regarding antibiotics. On the other hand, the early-biology students outperformed every other group on the item regarding radioactive milk, whereas the percentage of STEM and non-STEM students that answered that question correctly was similar. Additionally, only 51% of the general public answered the evolution question correctly, compared to 91% of the GenEd STEM students. This presumably reflects the fact that STEM majors have more classroom exposure to evolution than the average member of the public. Interestingly, the GenEd STEM students out-performed the early-biology students on this item; this may indicate a gap in the biology education of the majors, who are largely working on cellular and molecular biology in their coursework and research. The evolutionary-biology classes that cover evolution generally are taken after the introductory-biology course described in this study. However, 100% of the advanced students majoring in evolutionary biology answered this question correctly. The lowest scores among the general public on the antibiotics and evolution questions were from individuals who do not have any college education.

References

Megan Nieberding (Nieberding.17@buckeyemail.osu.edu) is a graduate student in the Department of Physics at Ohio State University in Columbus, Ohio. Sanlyn Buxner is an associate research professor of science education in the Department of Teaching, Learning, and Sociocultural Studies, Lisa Elfring is associate vice provost for instruction and assessment and associate specialist in molecular and cellular biology, and Christopher Impey is a university distinguished professor in the Department of Astronomy, all at the University of Arizona in Tucson, Arizona.