Introductory biology for nonmajors provides an opportunity to engage students with the complexity of life. In these courses, instructors also have the opportunity to experiment with course material and delivery, especially with an intent to overcome common misconceptions about biology. Fortunately, frameworks exist that can be integrated into a completely novel classroom framework: the AP biology curriculum and the tree of life. In addition, assessments are available that specifically address common misconceptions. I tested whether such a novel approach, covering the four big ideas in biology equally and structured around an accurate depiction of biodiversity as a branching history of evolution, can improve student comprehension of difficult biological concepts. In the end, I found that students improved significantly in their understanding of biology and were much less likely to have common misconceptions about difficult topics.

Introduction

One of the most fundamental issues in teaching biology to undergraduates is dealing with biological misconceptions (Anderson et al., 1990; Bishop & Anderson, 1990). Also, high school and early-career college students seem unable to understand the biological processes underlying major concepts such as genetic transfer (Lewis & Wood-Robinson, 2000). In fact, studies have shown that even biology majors suffer from persistent misconceptions, but that active-learning classrooms enhance understanding and reduce misconceptions (Nehm & Reilly, 2007). Additionally, Nehm et al. (2009) found that introductory biology textbooks reinforce the idea that evolution is one concept, rather than the unifying concept, of biology, and that this may reinforce misconceptions. Considering the challenges presented by student misconceptions and their reinforcement by textbooks, completely novel courses may be the best strategy in overcoming biological misconceptions.

Instructors in nonmajors biology classes have the opportunity to engage students with novel classrooms that may help overcome common misconceptions. Given that textbook frameworks have been found to be problematic (Nehm et al., 2009), alternative frameworks such as the AP Biology Curriculum may be useful in novel course construction. The AP curriculum promotes learning the four big ideas in biology: that evolution drives the diversity and unity of life (evolution: in the syllabus I call this “history”); that biological systems use energy and molecular building blocks (energy transfer); that living systems use information essential to life processes (in this class: genetics); and that biological systems interact (interactions – i.e., ecology) (College Board, 2011). Because the AP curriculum represents a bridge between high school and college, it is a good framework to present information to nonmajors in a biology course. However, covering all four big ideas equally can be challenging.

One way to help alleviate the stress of teaching nonmajors complex ideas, while covering the totality of biology, may be the use of an iterative teaching method. Hierarchical repetition (covering a topic multiple times within higher-order topics) may be an effective means to cover difficult topics, while not spending too many consecutive class periods on especially difficult topics. For example, cellular respiration can be introduced in animals, expanded in plants, and explored deeply in bacteria. The use of these concepts in different contexts represents cellular respiration as energy flow – a concept or unifying theme, rather than a trait linked to animals and peculiar to this group. Additionally, varying the context of the topic facilitates more avenues of learning and helps relate the unity of life around such concepts.

The tree of life is a hierarchical structure with nested groups of similar organisms that represent an evolutionary history. In addition, the tree of life is a unifying framework, providing exposure to unknown and unique taxa. Teaching the diversity of life is a less confrontational approach to evolution and illustrates the unity of life through shared biological processes. These biological processes can be repeated in each taxon, solidifying the relative similarity of all life on Earth. At the same time, the diversity of life poses stumbling blocks to student learning. For example, students utilize different biological concepts (and misconceptions) when learning about different taxa (Ha et al., 2006; Nehm & Ha, 2011). Additionally, lesser-known taxa have less information available, need more background material to present the concept, and are less likely to be covered in the students’ textbook. More time spent on lesser-known species also results in less time spent on familiar species. Students may lose interest in the course as the examples become more remote from their current understanding of life.

In order to overcome the issues associated with teaching a representative example of the diversity of life, an alternative course structure may be necessary. In the present study, I aimed to determine whether a class structured around the three eukaryotic branches of life (Unikonta such as fungi, animals, and amoebas that externally process their foods; Plantae such as algae and land plants that produce their own food using chlorophylls a and b and have cell walls made of cellulose; and Chromalveolates–Excavates [two groups] such as paramecia, kelp, and dinoflagellates that have a variety of characteristics but may share common ancestry) along with prokaryotes and viruses, subdivided into the four big ideas in biology (Table 1), can be an effective means of delivering introductory biology to nonmajors. This organization of life is based on the Tree of Life web project (http://tolweb.org) and is one hypothesis about the relationships of life on Earth and the history of its evolution. For prokaryotes I spent most of the time on Eubacteria, because there is more information available, but I did mention Archaea. Specifically, I assessed whether student performance on a test of common misconceptions improved significantly after participating in such a course. The test was generated from Project 2061, which promotes science education with a focus on testing and overcoming common misconceptions (http://assessment.aaas.org/). I hypothesized that covering the four big ideas equally and using the tree of life (http://tolweb.org) as a structure for discussing organisms would significantly decrease student misconceptions about these four big ideas and that, on average, students would be more scientifically literate in these difficult topics by the end of the course.

Table 1.
Schedule for Summer Session Biology 101.
Week 1: We will cover the four big ideas concerning Unikonta. 
Day 1: History 
Day 2: Energy acquisition and usage 
Day 3: Biological interactions in invertebrates 
Day 4: Reproduction in fungi 
Day 5: Body Plans Game; Exam 
Week 2: We will cover the four big ideas concerning Plantae. 
Day 1: History 
Day 2: Energy acquisition and usage in seed plants 
Day 3: Biological interactions in green algae 
Day 4: Information transfer in nonseed plants 
Day 5: Plant Adaptations Game; Exam 
Week 3: We will cover the four big ideas concerning Chromalveolates and Excavates. 
Day 1: History 
Day 2: Energy acquisition and usage in apicomplexa 
Day 3: Biological interactions in dinoflagellates 
Day 4: Information transfer in Paramecia 
Day 5: Pond Ooze Game; Exam 
Week 4: We will cover the four big ideas concerning bacteria and viruses. 
July 4th Holiday 
Day 2: History of and energy in bacteria and viruses 
Day 3: Biological interactions in Eubacteria 
Day 4: Information transfer in viruses and prions 
Day 5: Terraforming Game; Exam 
Week 1: We will cover the four big ideas concerning Unikonta. 
Day 1: History 
Day 2: Energy acquisition and usage 
Day 3: Biological interactions in invertebrates 
Day 4: Reproduction in fungi 
Day 5: Body Plans Game; Exam 
Week 2: We will cover the four big ideas concerning Plantae. 
Day 1: History 
Day 2: Energy acquisition and usage in seed plants 
Day 3: Biological interactions in green algae 
Day 4: Information transfer in nonseed plants 
Day 5: Plant Adaptations Game; Exam 
Week 3: We will cover the four big ideas concerning Chromalveolates and Excavates. 
Day 1: History 
Day 2: Energy acquisition and usage in apicomplexa 
Day 3: Biological interactions in dinoflagellates 
Day 4: Information transfer in Paramecia 
Day 5: Pond Ooze Game; Exam 
Week 4: We will cover the four big ideas concerning bacteria and viruses. 
July 4th Holiday 
Day 2: History of and energy in bacteria and viruses 
Day 3: Biological interactions in Eubacteria 
Day 4: Information transfer in viruses and prions 
Day 5: Terraforming Game; Exam 

Methods

Classroom

As a Ph.D. student at Iowa State University in the summer of 2011, I was the sole instructor for Biology 101, a 4-week introductory course for nonmajors that met every weekday for ~1.5 hours (the schedule is given in Table 1). The class had ~40 students, 35 of whom completed the pretest and posttest given for the present study. Active-learning techniques were used in all class periods (e.g., turn to your partner, note-taking pairs, and authentic inquiry). Class time was typically split between lectures and application of knowledge in student groups. I tested the students for comprehension on Friday of each week; these four tests consisted of a variety of question types, including multiple-choice and essays. All curriculum development was mentored by a senior faculty member at Iowa State University.

Assessment

To determine the misconceptions that students had, I used a standardized multiple-choice test with 20 questions generated at the AAAS Project 2061 Science Assessment Website (http://assessment.aaas.org/; whole test available upon request). These ranged from questions that high school students typically do extremely well on to questions they do very poorly on. There were five questions on each of the four big ideas: evolution, energy, ecology, and genetic transfer (Table 2). Each question had four possible responses, and the three incorrect ones in each case contained elements of a common misconception. For the assessment, I gave the students the entire, 20-question test on the first day of class and again during the last week of the course. I awarded students a small number of extra credit points for completing the assessment but told them that the results would have no effect on the number of points they received. I allowed students the full amount of time necessary to complete the assessment. All procedures were approved by the Institutional Review Board of Iowa State University.

Table 2.
List of questions given to each student at the beginning and end of the course (generated from AAAS Project 2061; the whole test is available, with multiple-choice options, at http://assessment.aaas.org/).
Evolution 
A species lives in a particular environment. What is TRUE about the environment that the species lives in and about how the species will look over thousands of years? 
Individual members of a species could have differences in inherited characteristics that affect which of the following? 
Could individuals of a species look different today than individuals of the same species did many generations ago? Why or why not? 
Some animals, such as a cat and a dog, have many similarities. Others, such as a fish and a bird, have fewer similarities. What do scientists think is TRUE about the ancestors of these animals? 
What is TRUE about maple trees and lizards? 
Energy Transfer 
Which of the following statements is TRUE about the carbon dioxide that is used by plants? 
Which of the following is TRUE about food? 
Which of the following is a source of food for animals? 
Which of the following is TRUE about the sugar molecules in plants? 
As an animal grows, what happens to the food that it eats? 
Interactions 
Which of the following statements about competition between animals is TRUE? 
Which of the following statements about competition between plants is TRUE? 
Which of the following statements about competition between animals is TRUE? 
The diagram below shows the feeding relationships between populations of plants and animals in an area. The arrows point from the organisms being eaten to the organisms that eat them. A new species that eats only mice becomes part of this food web, greatly reducing the number of mice in this area. Using only the relationships between the plants and animals shown in the diagram, what effect would the new species have on the caterpillar population if the number of foxes stays the same? 
Similar diagram. A disease kills all of the robins in the area. … [W]hich population of organisms will increase after the robins die? 
Genetics 
The eye color of children often resembles the eye color of their parents. Which of the following is genetically passed from parents to children? 
Like most animals, mice reproduce sexually. The skin cells of a mouse each contain 40 chromosomes. How many chromosomes does a sperm cell of a male mouse contain?
In sexually reproducing organisms, such as humans, which of the following statements is TRUE about the DNA found in the cells of their children? 
A change commonly referred to as a mutation occurs to a DNA molecule in an organism's skin cell before the organism reproduces. When the organism reproduces, how many of its children will have the mutation? 
Which of the following statements is TRUE about the genetic information in the cells of the leaves and the cells of the flowers of the same plant? 
Evolution 
A species lives in a particular environment. What is TRUE about the environment that the species lives in and about how the species will look over thousands of years? 
Individual members of a species could have differences in inherited characteristics that affect which of the following? 
Could individuals of a species look different today than individuals of the same species did many generations ago? Why or why not? 
Some animals, such as a cat and a dog, have many similarities. Others, such as a fish and a bird, have fewer similarities. What do scientists think is TRUE about the ancestors of these animals? 
What is TRUE about maple trees and lizards? 
Energy Transfer 
Which of the following statements is TRUE about the carbon dioxide that is used by plants? 
Which of the following is TRUE about food? 
Which of the following is a source of food for animals? 
Which of the following is TRUE about the sugar molecules in plants? 
As an animal grows, what happens to the food that it eats? 
Interactions 
Which of the following statements about competition between animals is TRUE? 
Which of the following statements about competition between plants is TRUE? 
Which of the following statements about competition between animals is TRUE? 
The diagram below shows the feeding relationships between populations of plants and animals in an area. The arrows point from the organisms being eaten to the organisms that eat them. A new species that eats only mice becomes part of this food web, greatly reducing the number of mice in this area. Using only the relationships between the plants and animals shown in the diagram, what effect would the new species have on the caterpillar population if the number of foxes stays the same? 
Similar diagram. A disease kills all of the robins in the area. … [W]hich population of organisms will increase after the robins die? 
Genetics 
The eye color of children often resembles the eye color of their parents. Which of the following is genetically passed from parents to children? 
Like most animals, mice reproduce sexually. The skin cells of a mouse each contain 40 chromosomes. How many chromosomes does a sperm cell of a male mouse contain?
In sexually reproducing organisms, such as humans, which of the following statements is TRUE about the DNA found in the cells of their children? 
A change commonly referred to as a mutation occurs to a DNA molecule in an organism's skin cell before the organism reproduces. When the organism reproduces, how many of its children will have the mutation? 
Which of the following statements is TRUE about the genetic information in the cells of the leaves and the cells of the flowers of the same plant? 

Statistical Analysis

I used a t-test to evaluate pretest and posttest scores by gender and for individuals, as well as average scores for each section. I used Fisher's exact test to evaluate the binomial outcomes of correct–incorrect responses based on individual questions.

Results

Thirty-five students completed both assessments. There was no significant difference between genders before or after the test, nor was gender a predictor of improvement. Overall, student scores were significantly higher after the course (before: 56.75%, after: 71.45%; t = 5.13, P < 0.001). Students improved significantly on the evolution, genetics, and interaction sections of the test (all P < 0.001). However, students did not significantly improve their scores in energy transfer (t = 1.18, P = 0.24). Table 3 summarizes the percent correct before and after the course and whether the rate of success on a question was significantly greater for the posttest than the pretest.

Table 3.
Summary of questions on assessment. Values represent percentage of students that responded correctly. Bolded “after” scores are significantly more frequently answered correctly than “before” (P < 0.05).
QuestionBeforeAfterNational High School Average
1 93% 97% 75% 
2 58% 86% 58% 
3 50% 74% 29% 
4 13% 43% 18% 
5 58% 83% 40% 
6 50% 42% 44% 
7 95% 94% 71% 
8 55% 66% 51% 
9 38% 69% 42% 
10 0% 6% 9% 
11 65% 91% 49% 
12 78% 97% 64% 
13 93% 100% 87% 
14 38% 51% 27% 
15 100% 94% 74% 
16 83% 94% 78% 
17 60% 91% 61% 
18 53% 83% 55% 
19 5% 11% 16% 
20 50% 57% 40% 
QuestionBeforeAfterNational High School Average
1 93% 97% 75% 
2 58% 86% 58% 
3 50% 74% 29% 
4 13% 43% 18% 
5 58% 83% 40% 
6 50% 42% 44% 
7 95% 94% 71% 
8 55% 66% 51% 
9 38% 69% 42% 
10 0% 6% 9% 
11 65% 91% 49% 
12 78% 97% 64% 
13 93% 100% 87% 
14 38% 51% 27% 
15 100% 94% 74% 
16 83% 94% 78% 
17 60% 91% 61% 
18 53% 83% 55% 
19 5% 11% 16% 
20 50% 57% 40% 

Discussion

Overall, this course was highly successful in overcoming student misconceptions and misunderstandings about important biological processes. Questions that did not improve considerably were easily identified as components missing from the class. I probably spent too much time at the organismal level of genetics and energy flow, and not enough time at the molecular level. However, this material could have been covered within the context of the course without changing its format or scope.

Improved Understanding

Specifically, students improved their understanding that inherited traits can be beneficial for a variety of reasons, including mate attraction and food acquisition. At the beginning of the course, students wanted to limit the usefulness of inherited traits to one or the other. Students also reduced their misconception that individuals can change and pass those traits on to offspring, and eliminated their misconception (0% response) that species do not change after many generations and look identical to the ancestor population. There was, however, a persistent misconception that all individuals can change a little and pass those changes on to their offspring. Students also dramatically improved their understanding of shared common ancestry: at the beginning of the course, 13% of the students answered that distantly related species share an ancient common ancestor, compared with 42% at the end of the course. The biggest reduction in responses was that far fewer students (8% vs. 30%) responded that cats, dogs, fish, and birds do not share any common ancestors. The final question in evolution was similar, asking about the characteristics of maple trees and lizards. At the end of the course, students had eliminated their misconception that there is no way to compare maple trees and lizards, and reduced their misconception that there are differences but no similarities between the two species (33% vs. 19%). Misconceptions about evolution and how to overcome them have been the focus of much research. Even the textbooks used in biology courses have been determined to contribute to these misconceptions (Nehm et al., 2009; Tshuma & Sanders, 2015). In addition, researchers have found that classroom discussion, as an active learning element, can help overcome misconceptions about evolution (Tran et al., 2014). Our study is in line with these previous studies, in that the biggest gains were seen in the evolution assessment, and the class did not follow the textbook and used extensive active learning, including classroom discussion.

In the energy transfer section, students significantly reduced their misconception that sugar molecules are one of many food sources for plants and that the sugar comes from water and minerals, instead answering correctly that the sugar molecules are made by the plants. Students also reduced their misconception that plants do not compete for resources in general. Students improved their understanding that competition can include two animals foraging on grass, rather than just direct and aggressive forms of competition, and that competition can be for any resource that is limited. On the genetics section, students made significant improvements in their understanding that gametes contain half the chromosomes of a somatic cell and that exactly half of the DNA in a sexually produced offspring comes from each parent, which they previously thought was variable and unpredictable. These results are in line with findings that students have linked misconceptions based on their intuitive ways of thinking (Coley & Tanner, 2015). Specifically, the researchers found that seemingly disparate misconceptions stem from common ways of thinking. In our case, this could be due to anthropocentric, essentialist, or teleological thinking that makes plants less familiar, DNA a mirror of the structure in which it is found, and competition an active process that involves behaviors that can be easily observed (Coley & Tanner, 2015). If so, the class may have made a positive impact not only on comprehension of these topics, but also on the general scientific thinking of the students.

Persistent Misconceptions

Common misconceptions persisted for some questions – for example, that carbon dioxide is combined with oxygen to make sugar molecules and that it is food for plants (but students did eliminate the misconception that carbon is absorbed through the roots). Students also continued to think that water and minerals were a better answer than fat as a source of food for animals. Almost no students answered correctly when asked about the utilization of food, and the most common misconception was that food is either used for energy or excreted as waste, with the better answer being that some food is changed into new substances that become part of the animal's body. Galvin et al. (2015) also found that respiration and photosynthesis are common problem areas in biology, with preservice biology teachers performing very poorly on this assessment. When asked about how the feeding relationships in a food web change when a new species is introduced, students were persistently unable to predict trophic cascades. It has long been understood that secondary students have multiple misconceptions about food webs (Griffiths & Grant, 1985). The persistence of this misconception is not surprising, because the question expects students to know direct and indirect effects. Finally, students had persistent misconceptions that a skin cell will be inherited by some offspring and that the genetic information in leaves and flowers is different. Cakir and Crawford (2001) identified conceptual misunderstandings of inheritance in preservice secondary educators, which would suggest that many students receive poor training and possibly are taught misconceptions during their high school training.

In summary, this course was able to utilize current, accurate phylogenies to structure the four phases of the course, with the exception that the fourth week covered multiple branches of prokaryotic life. I was also able to give equal time to each of the four big ideas of biology, ensuring that each big idea was presented as equally important. In addition, the test of misconceptions showed that students were at a failing level (57%) of biology understanding when they entered the class, but students were at a solid C (71%) average when they left the class. Despite the fact that significant time was given to topics that are either reduced or eliminated commonly in introductory biology, students were engaged in class, participated extensively, succeeded on formative and summative assessments, and successfully broke common misconceptions.

Limitations & Directions for Future Research

Although the results of this study are limited to a single course and a single event, it represents an initial test of the efficacy of such a novel introductory biology structure. During the development of the course, I had to make difficult decisions about what material to include or exclude. In retrospect, I would have excluded the discussion of viruses and focused the final week on prokaryotes. In a longer-term course, I would have liked to have five sections, separating out Eubacteria from Archaea. The discussion on Archaea should definitely be final, as it represents an unfamiliar group, but at the end of the semester most of the discussion could focus around similarities and differences of this group compared with others. Finally, in any version of the course, more time should be spent on energy and genetic transfer. I would like to have spent more time discussing the processes of cellular respiration and photosynthesis as cycles, and similarly to have spent more time on genetics as a physical inheritance of DNA, a topic that has been reported as very difficult for students (Lewis & Wood-Robinson, 2000). In a larger class, the logistics of some activities would be challenged, especially the ecology studies done outside and the extensive amount of group learning. However, recent research has found that the size of a class does not determine the efficacy of such active learning; rather, understanding and closing the learning gap among student groups relies on intensive practice and active-learning exercises (Haak et al., 2011). This course outline supports both of these objectives.

A second fundamental change for this course would be to spend time working specifically with the Tree of Life website (http://tolweb.org). At the beginning of the course, I used the website on the front screen in the classroom to click through the tree of life from the “root” to find chimpanzees. This showed students that there is an ancestry to all primates, an ancestry made of organisms that look nothing like chimpanzees. I believe that it also illustrated the significant diversity of life, which they had no idea existed. In future iterations of the class, I will follow up on this example by revisiting the tree and discussing where we are for the class period. It should also be useful, periodically – especially when we are talking about physiological processes such as photosynthesis – to revisit the tree and highlight all of the locations where a characteristic is found. It's then possible to discuss characteristics that are conserved from a common ancestor and those that may have arisen independently. This process allows for review of previously discussed groups and previews of groups yet to be discussed. All these activities work to reinforce the relationship of diverse life and reiterate important facts for understanding.

I thank Dr. James Colbert for his pedagogical mentoring during this process. This work was supported by the Knaphus fellowship at Iowa State University, without which I would not have been able to develop this course, nor conduct this study. I am also thankful for the financial support the position provided me, and the flexibility it gave me to deliver an innovative course.

References

References
Anderson, C.W., Sheldon, T.H. & Dubay, J. (
1990
).
The effects of instruction on college nonmajors’ conceptions of respiration and photosynthesis
.
Journal of Research in Science Teaching
,
27
,
761
776
.
Bishop, B.A. & Anderson, C.W. (
1990
).
Student conceptions of natural selection and its role in evolution
.
Journal of Research in Science Teaching
,
27
,
415
427
.
Cakir, M. & Crawford, B. (
2001
).
Prospective biology teachers’ understanding of genetics concepts
.
[Presented at the Annual Meeting of the Association for the Education of Teachers in Science.]
Coley, J.D. & Tanner, K. (
2015
).
Relations between intuitive biological thinking and biological misconceptions in biology majors and nonmajors
.
CBE Life Sciences Education
,
14
,
ar8
.
College Board
(
2011
).
AP Biology: Curriculum Framework 2012–2013
. Available at http://media.collegeboard.com/digitalServices/pdf/ap/10b_2727_AP_Biology_CF_WEB_110128.pdf.
Galvin, E., Simmie, G.M. & O'Grady, A. (
2015
).
Identification of misconceptions in the teaching of biology: a pedagogical cycle of recognition, reduction and removal
.
Higher Education of Social Science
,
8
(
2
),
1
8
.
Griffiths, A.K. & Grant, B.A. (
1985
).
High school students’ understanding of food webs: identification of a learning hierarchy and related misconceptions
.
Journal of Research in Science Teaching
,
22
,
421
436
.
Ha, M., Lee, J.K. & Cha, H.Y. (
2006
).
A cross-sectional study of students’ conceptions on evolution and characteristics of conception formation about it in terms of the subjects: human, animals and plants
.
Journal of Korean Association for Research in Science Education
,
26
,
813
825
.
Haak, D.C., HilleRisLambers, J., Pitre, E. & Freeman, S. (
2011
).
Increased structure and active learning reduce the achievement gap in introductory biology
.
Science
,
332
,
1213
1216
.
Lewis, J. & Wood-Robinson, C. (
2000
).
Genes, chromosomes, cell division and inheritance – do students see any relationship?
International Journal of Science Education
,
22
,
177
195
.
Nehm, R.H. & Ha, M. (
2011
).
Item feature effects in evolution assessment
.
Journal of Research in Science Teaching
,
48
,
237
256
.
Nehm, R.H., Poole, T.M., Lyford, M.E., Hoskins, S.G., Carruth, L., Ewers, B.E. & Colberg, P.J.S. (
2009
).
Does the segregation of evolution in biology textbooks and introductory courses reinforce students’ faulty mental models of biology and evolution?
Evolution: Education and Outreach
,
2
,
527
532
.
Nehm, R.H. & Reilly, L. (
2007
).
Biology majors’ knowledge and misconceptions of natural selection
.
BioScience
,
57
,
263
272
.
Tran, M.V., Weigel, E.G. & Richmond, G. (
2014
).
Analyzing upper level undergraduate knowledge of evolutionary processes: can class discussions help?
Journal of College Science Teaching
,
43
,
87
97
.
Tshuma, T. & Sanders, M. (
2015
).
Textbooks as a possible influence on unscientific ideas about evolution
.
Journal of Biological Education
,
49
. In press.