One way to structure, teach and prob students’ knowledge of the theory of evolution through natural selection (ENS), is to divide it into key concepts (Bishop & Anderson, 1990; Mayr, 1982; Nehm & Reilly, 2007; Tibell & Harms, 2017). However, different researchers use different combinations of key concepts. For example Bishop and Anderson (1990) study students’ understanding of ENS based on three key concepts, while Nehm and Reilly (2007) recognizes seven and Tibell and Harms (2017) use nine in connection with three main principles. The following paragraph outlines both the understanding of natural selection and five of the previously used key concepts (italicized) adopted here. In addition, we have a special focus on the connection between different organizational levels and how the students express time and generations.
Genetic changes such as random mutations and genetic recombination in the organisms’ genomes, are the origin of variation. It is important to understand that genes and other genetic material (genotypes), through interactions with environmental factors, lead to individual variation, constituted as variation of individuals phenotypes (morphology, structure, behavior and other characteristics). Offspring inherit their complements of genetic materials from their parents and thus, will share the majority of the phenotypic traits as well. Numerous factors influence organisms’ survival, for example the availability of nutrients or energy and presence of predators. Organisms with traits that confer advantages over their competitors, in a specific environment, will have higher probabilities of surviving to reproductive maturity. This results in differential survival, and genes carried by successful individuals are likely to become more frequent in successive generations. Hence, populations evolve in particular directions (Mayr, 1982), resulting in population change over time. Thus, an additional factor to handle when reasoning about natural selection is time, that is, a new trait will not be dominant in the population until after many generations. This is emphasized in the following definition of evolution in the Henderson dictionary of biology: “…. the development of new types of living organisms from pre-existing types by the accumulation of genetic differences over long periods of time.” (Lawrence, 2005, p. 218) Therefor, the learners must develop the ability to connect events like mutations with nanosecond timeframes to individuals life spans and much longer processes spanning multiple generations and even deep geological time (Tibell & Harms, 2017). It should be recognized that this is a gross simplification because sudden events like an asteroid strike or flood may cause very rapid changes in populations’ gene frequencies.
In summary, ENS can be said to encompass five key concepts, at least in a simplified form, which are used as reference points for the scientific perspective in this study. However, these concepts will not make much sense to learners unless they are given meaning by application in comprehensible examples like the evolution of fast predators like cheetahs, or plants with water storing leaves like succulents. The concepts are given meaning in such explanations of how species evolved from common ancestors into the diverse lifeforms we can observe today. The difficulties lie in creating scientific explanations of such examples.
Alternative conceptions
The advent of the theory of natural selection enabled explanations of the diversity of living organisms without introducing some kind of guiding force or inherent goal in evolution (Mayr, 1982). However, students at all educational levels tend to use pre-Darwinian reasoning (Harms & Reiss, 2019; Mayr, 1982; Nehm & Schonfeld, 2008) characterized by; explanations based on intentionality, teleology, anthropomorphism, and essentialism (Coley & Tanner, 2015; Ware & Gelman, 2014).
To explain a change based on its outcome or purpose is referred to as teleological. This lead to the misconception that variation occurs through direct response to needs evoked by environmental changes (Southerland, Abrams, Cummins, & Anzelmo, 2001). Or that traits acquired (based on purpose or intention) by an individual during its lifetime. Anthropomorphic reasoning ascribes to organisms’ human attributes, such as the ability to plan for the lives of future generations (Coley & Tanner, 2015) (together with implied super-human ability to modify their characteristics accordingly). In many cases the intention behind the change originate nature itself, acting as an agent (Gregory, 2009).
Research has also shown that many learners perceive of individuals of a species as sharing a common essence or type, disregarding variation between individuals as inconsequential (Gelman & Rhodes, 2012). Applied on evolutionary change, this conception may lead to the idea that evolutionary change is a process of altering the common essence, and with it all members of the species, instead of it being a change in the distribution of a trait in a population (Gregory, 2009). This alternative conception is referred to as essentialism.
Moreover, research has shown that students have difficulties with both short time and deep timescales in natural selection (Ferrari & Chi, 1998). Students therefore often fail to perceive evolutionary changes as a continuous process of genetic change that involves extremely rapid alterations (e.g., mutations), and responses to selective pressures that act at enormously varying timescales, including gradual change over thousands of generations. Students also tend to conceptualize natural selection as proceeding via intermittent events (Harms & Reiss, 2019), in which species adapt by fixing specific problems and then remain more or less the same until another problem that must be fixed arise. For convenience, this is referred to as the alternative conception of natural selection as an event, or simply Event.
In summary, students have to handle both different levels of organization and time scales in order to be able to move from a goal-directed, intentional, way of reasoning to see that natural selection requires variation within the population that occurs by random events, is present before any selection can occur, and that the variation is not a consequence of environmental pressure (Tibell & Harms, 2017).To monitor this movement in the way of reasoning, we need valid methods for investigating students’ conceptions.
The nature of alternative conceptions
The method applied for investigating students’ conceptions depend to some degree on assumptions regarding how people form and link ideas. Some researchers view students’ knowledge as coherent intutive conceptual frameworks (Coley & Tanner, 2015) while others view their knowledge as a more fluid collection of smaller phenomenological primitives (diSessa, 1993). This is an ongoing area of research with relevance to the field of evolution education. Recently the debate has been reheated by Gouvea and Simon (2018), who problematized the multiple choise instrument used by another team of researchers (Coley & Tanner, 2015). The critisism was that by using ambiguously formulated questions and alternatives Coley and Tanner was ‘tricking’ students into picking the alternatives representing the alternative conception, thus, failing to capture the students’ real conceptions. When the formulations were changed to state more directly what was really meant, Gouvea and Simon (2018) found that, students did better than with the original test items used by Coley and coworkers. Gouvea and Simon (2018) claim that their results are difficult to explain using the notion of ‘intuitive ways of knowing’ that Coley and Tanner (2015, p. 1) termed cognitive construals.
Studying the nature of students conceptions can also be done by analysing the consistency of their use in diffeernt contexts, where the student need to transfer their understanding (Pugh, Koskey, & Linnenbrink-Garcia, 2014) from one context to another (Göransson, Orraryd, Fiedler, & Tibell, 2020), or swiching medium eg, written to drawing or animation (Kampourakis, 2007), as well as social context, e.g., individual to colaborative. More research is clearly needed to resolve this issue. We contribute with a study of student-generated animations, created in a colaborative setting.
Visual representations of natural selection
It has been stated that visual representations are indispensable in biology education (Treagust & Tsui, 2013). Available visual representations of evolution, for example, cladograms and phylogenetic trees can be difficult to interpret (Catley, Novick, & Shade, 2010). However, a cladogram or phylogenetic tree is constructed to represent the history of the unity and diversity of living organisms, not the mechanisms responsible for changes in species (Matuk & Uttal, 2012) at least not without supplementary information. Consequently several misunderstandings related to the interpretation of temporal aspects of evolutionary trees have been reported (Gregory, 2008), and they do not seem to facilitate an explicit understanding about temporal aspects of evolution (Stenlund & Tibell, 2019).
The public image of evolution is strongly influenced by historical, pre-Darwinian, imagery (Archibald, 2014). For example, 42 % of undergraduate students asked to draw an image of evolution in a study presented by Matuk and Uttal (2012, p. 122) generated some variant of the iconic “March toward Man” image. The perception that life evolves on a ladder, in a linear manner, is referred to as the great chain of being (Abrams & Southerland, 2001), is common. That is not to say that there are no representations of the mechanisms involved, for instance there is a plethora of animations and simulations available as educational resources on the internet. These, however, are very diverse and not bound by disciplinary rules, as shown in a study by Bohlin, Göransson, Höst, and Tibell (2017). However, using student-generated animations to give new insights into student conceptions is still unexplored.
Assessment- from text only to multimedia
In science education, including biology education, there is a proliferation of explanatory animations (Lowe et al., 2017; Phillips, Norris, & Macnab, 2010). The old textbooks are being replaced with new multimedia displays that have increasing degrees of interactivity. However, this shift from text to animation is not mirrored in the assessment methods (Nielsen et al., 2020).
Student conceptions of evolution and natural selection have been probed using interviews, and various kinds of paper-and-pen tests, ranging from multiple choice to essays (e.g. Anderson et al., 2002; Bishop & Anderson, 1990; Nieswandt & Bellomo, 2009). A comparison has shown that each method of assessment may reveal different aspects of the same subjects’ conceptions (Nehm & Schonfeld, 2008). The context of test items may also influence the levels of understanding and patterns of alternative conceptions displayed (Göransson et al., 2020; Nehm et al., 2012). Moreover, most of these tests are lexical, thereby preventing students from using other media, like pictorial, to represent their understanding, or at least severely constraining their opportunities to do so.
This might be problematic. If a student is expected to write what s/he might have learnt from watching an animation or simulation, there is a risk that the translation between modes may interfere with the result (Lowe et al., 2017). Assuming that each representational mode has strengths and weaknesses that constrain what can be expressed (Prain & Tytler, 2012), the assessment may not provide a valid representations of the students’ conceptions. Lowe et al. (2017) also report that the written explanations are often insufficient representations of what learners acquired from studying an animation.
It may be important to distinguish two types of representations: descriptive and depictive (e.g. animations) (Schnotz, 2002). The first is by necessity symbolic as the letters in a word bear no resemblance of the object they represent, whereas the second type can be more analogous to and often depict the referents. Due to such differences, some aspects of a topic may be easily represented in one mode but troublesome in the other. For instance, a depictive representation has the potential to convey simultaneous events directly while the linear format of the descriptive representation constrains that possibility (Prain & Tytler, 2012).
Following this reasoning, there is a clear need to explore what student-generated dynamic representations can reveal about student’s conceptions. Akaygun (2016) claim that student-generated animations can be used as powerful assessment tools, particularly to reveal conceptions of a dynamic character. Detailed tests of such claims, and analyses of the scope for using student-generated multimedia animations to investigate students’ conceptions are clearly warranted (Lowe et al., 2017; Mintzes, Wandersee, & Novak, 2001; Rector et al., 2013).
Stop motion animations in biology education
Stop-motion is an open format and intuitive technique for generating animations is (Hoban & Nielsen, 2010) that has suggested utility for supporting students conceptual development (Farrokhnia, Meulenbroeks, & van Joolingen, 2020) Stop motion is a technique where you physically move objects and photograph them one frame at a time. Displaying the photos in a sequence create the illusion of movement. By re-representing a phenomenon in a series of different modes, the learner has to re-evaluate and develop his or hers ideas (Berg, Orraryd, Pettersson, & Hultén, 2019; Hoban & Nielsen, 2010). The animation is produced by making small changes over a long time, analogously to evolution, which generally involves small, incremental changes over long periods. Therefore, it seems appropriate to investigate the use of this method for generating animations to explain how species change.
A study on preservice teacher students’ views of using stop-motion activities in biology teaching (Karakoyun & Yapici, 2018) concluded that the students thought it was a good approach to develop cooperation, communication and creativity. On the other hand, they thought it was difficult to invent scenarios to implement the technique. Several studies have also found that generating stop-motion animations has potential to help students achieve stipulated learning objectives regarding cellular processes, and molecular biology (Deaton, Deaton, Ivankovic, & Norris, 2013; Kamp & Deaton, 2013; Peterson & Ngo, 2015). The main finding from these studies is that students seemed to enjoy this creative way of working. A common feature is that the content concerned a microscopic scale and relatively limited time scales. Some studies have considered the utility of student generated stop motion animations for learning content associated with larger spatial and time scales, e.g. geology (Mills, Tomas, & Lewthwaite, 2019). However, there is a lack of studies on the possible value of using student generated animations as diagnostic tools for revealing students’ conceptions, despite research showing a need for such knowledge.
Aim
This exploratory study concerns how students handle the task to explain evolution through natural selection by collaboratively generating a stop-motion animation. The three main aims are to investigate …
- … which means of expression do students use when they are to express their knowledge in student-generated stop-motion animations.
- … what concepts are students able to represent in stop-motion animations.
- … how the conceptions, expressed in stop-motion animations, relate to written explanations of evolutionary change and earlier research literature.
By pursuing these aims, this work creates a starting point for the development of a teaching sequence for teaching evolution through natural selection, including student collaborator created stop-motion animations.