What Can Student-Generated Animations Tell Us About Students’ Conceptions of Evolution?

A large body of research investigate student´s conceptions and emphasizes that students have alternative conceptions about causes of evolutionary changes. The conventional way to monitor students’ conceptions are through inventories where researchers analyze their written answers. However, textbooks are being increasingly complemented with, or even replaced by, various multimedia materials and multiple modes are used to communicate evolutionary processes. This has profound implications for students’ learning, and the test format may inuence which knowledge they present. The goal of this exploratory study is therefore to expand the understanding of students’ conceptions of evolution through natural selection by applying student-generated stop-motion animations to disclose students’ conceptions. Forty-seven Swedish upper secondary school students generated eighteen animations concerning evolution through natural selection. We analysed the animations qualitatively using content analysis recording key concepts, alternative conceptions and connections in organizational levels and time. This analysis was related to the analysis of the students written explanations of a case of evolutionary change.


Introduction
Knowledge of students' conceptions of a topic is essential not only for teachers' ability to orchestrate effective and appropriate learning situations, but also to assess students' progress (Smith & Tanner, 2010). The most common way to test conceptual understanding is through written tests, often using certain test packages (Anderson, Fisher, & Norman, 2002;Nehm, Beggrow, Opfer, & Ha, 2012). However, textbooks are being increasingly complemented with, or even replaced by, various multimedia materials (Lowe, Boucheix, & Fillisch, 2017), and scientists are increasingly using multiple modes to develop and communicate theories (Ainsworth, Prain, & Tytler, 2011;. This has profound implications for assessments of students' knowledge, because the form of tests in uences the knowledge they present (Nehm & Ha, 2011). Thus detailed investigation of the impact of incorporating multimedia representations on students' learning and assessment of their knowledge is needed (Lowe et al., 2017; Nielsen, Georgiou, Jones, & Turney, 2020; Rector, Nehm, & Pearl, 2013) To address this need, we have explored the indications of students' knowledge of evolution via natural selection provided by creation of multimedia, stop-motion animations, and relating this to a common written test. Here, we describe how students represented how organisms can undergo evolutionary change in a collaborative animation generation task and analyze how they expressed ve key concepts, three alternative concepts, evolutionary time, and how they make connections between organizational levels.

Background
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 ve 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 in uence 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 speci c 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 de nition 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 simpli cation because sudden events like an asteroid strike or ood may cause very rapid changes in populations' gene frequencies.
In summary, ENS can be said to encompass ve key concepts, at least in a simpli ed form, which are used as reference points for the scienti c 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 di culties lie in creating scienti c 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 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 di culties 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 xing speci c problems and then remain more or less the same until another problem that must be xed 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 uid collection of smaller phenomenological primitives (diSessa, 1993). This is an ongoing area of research with relevance to the eld 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 di cult 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 . Available visual representations of evolution, for example, cladograms and phylogenetic trees can be di cult 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 in uenced 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 , 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 studentgenerated 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 It may be important to distinguish two types of representations: descriptive and depictive (e.g. animations) (Schnotz, 2002). The rst 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 ( . 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 di cult 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 nding 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 … 1. … which means of expression do students use when they are to express their knowledge in studentgenerated stop-motion animations.
2. … what concepts are students able to represent in stop-motion animations.
3. … 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.

Methods
Participants of the study The subjects of this study were forty-seven students from two classes (aged 16-17 years), which were attending the national science program in Swedish upper secondary school (Swedish gymnasium). The teachers of these classes were willing to include this task as compulsory in the evolution segment of the basic biology course but participation in the study was voluntary. However, all students agreed to include their animation in the study while eleven (of the total 58) did not contribute with written explanations.
Design of the study Initially, a 15-minutes introduction to the stop-motion technique was conducted by experienced media educators. They also provided some of the equipment needed for generating the animations and who assisted in solving technical problems during the animation workshops.
The students were divided into smaller groups of 2-5 students and asked to generate stop-motion animations, with the following instruction: "Organisms can undergo evolutionary change. Generate an animation that shows how this process works." It was up to the students to choose organisms, materials, story, and context for their explanation with peers in a parallel program who had not taken the biology course as the intended audience.
The small groups had three hours to generate their animations, via the following steps: 1. Creation of a short visual manuscript; a storyboard.
2. Building models and a set or 'stage'.
3. Taking a series of digital photos of the models and moving them a small amount between each photo.
4. Finally, editing the animation, adding narration, sound, and/or other effects.
After this procedure, the students were asked to individually write responses to a written question, retrieved from the ORI inventory of natural selection ( These explanations were used in this study as a reference of the student's level of understanding of ENS.
The two questions above ask the students to explain essentially the same process but illustrated in two different representational modalities. The time consumed to do this is also different, the stop-motion animation takes 3 hours and to answer the written item about 10-15 minutes. In addition, the written response was requested after the completion of the stop-motion animation episode was nished.

Stop motion animation
The students used a digital camera connected to a tabletop computer with the stop-motion software (iStop-motion) to record the movies. The and models was mainly made by clay, but drawings, cut-outs, other material at hand, and placed in a set or scene. (Hoban & Nielsen, 2010). The movies were then exported to movie editing software (iMovie) and sound and sometime other effects was edited in the nal animation.

Analysis
The unit of analysis was de ned as one representation, animation, or written response. Each representation was considered in its totality for any occurrence of the codes, and several codes could be assigned to the same unit of analysis.

Movies
Regarding the inductive analysis each of the animations was brie y described, then their salient, visual attributes were subjected to inductive categorization and deductive content analysis. The inductive analysis pursued the natural discovery of themes, both concerning the multimodal expressions and the disciplinary content. Emergence of a theme could be expressed in one animation (Amundsen, Weston, & McAlpine, 2008), while multiple themes could also relate to a single animation. Each author initially perused the same 18 animations, followed by collectively discussing any emerging themes related to natural selection. A few cases had to be discussed before the authors reached agreement.
Concerning the design features of the stop-motion animations the following categories emerged: what sort of organism the students were choosing, how variation in characteristics were illustrated, and how selection pressure was exempli ed. Furthermore, reinforcing supplements such as illustrative sounds, music, oral narration or written text were registered.
The deductive analysis (Mayring, 2002), was based on previous research on students' understanding and developed from a compressed version of a criteria catalogue developed by Tibell and Harms (2017) (Table 1). Table 1: List of key-concepts of evolution and alternative concepts including criteria for analysis.

E1 -Variation between individuals
Any differences in phenotypes -phenotypic variation. Indications of variation present.

E2 -Origin of variation
Variation arises on a genetic level. Coupling between mutations and the variation of traits is necessary.

E3 -Inheritance (including reproduction)
Offspring inherit traits from parents and pass them on to successive generations.

E4 -Differential survival
Not all individuals of a generation survive to reproduce for reasons such as limitations of resources or predator attacks.

E5 -Change in population
Favorable traits become more frequent in populations over generations.

A1 -Intentionality
Directed evolution where a new trait appears after a change in the environment. Indication that changes occur because of an ultimate goal or by human-like intentions and ability to plan for a far future.

A2 -Essentialism
Transformation of all individuals in a population. Unifying essence instead of variation.

A3 -Natural selection as an event
Major evolutionary changes occur in less than three [1] generations.

T1-Organizational levels
Connections between organizational levels, from genes to population T2 -Time Illustration/manipulation of tempo. (Fast forward or slow motion) Representations that conveyed concepts were coded accordingly to allow qualitative description of whether and how students included the underlying key concepts and alternative conceptions in their representations.

Written explanations
The 47 written explanations was also analyzed deductively using the same criteria catalogue as described above, and focused on the message manifested in each response (Graneheim & Lundman, 2004).

Evaluation of the intervention
The students evaluated the session on a scale from 1-9 to describe 1) if creating stop-motion animations were developing and fun, or 2) if it was demanding.

Results
The evaluation resulted in a positive result. In general, the students appeared stimulated by crating stopmotion animations. They did not experience it as particularly demanding (3.8) and found the session to be developing and fun (6.7). This is remarkable since making stop-motion animations is tedious work. In the evaluations there were several remarks about how this was different from and more fun than the usual science classes.
How are the concepts represented/illustrated in the animations?
The length of the 18 stop-motion animations ranged between 21-83 seconds with a mean of 45 seconds. We were interested in the spontaneous choices in the 18 animations.
When choosing the organisms, traits, and selection pressure, all the groups used animal ( Table 2). Fourteen animations (78%) tried to do more or less realistic animals. Some of these were human like or fantasy animals. Only four groups (22%) chose to make symbolic, but still to some extent animal like, organisms ( Table 2). Two thirds of the animations did either not show any generation shifts at all (6%), or only the parental or one generation offspring (3%). Six of the animations (33%) showed three or more generations. (Table 2). The represented "population" on which natural selection acted were in 50% of the animations more than three individuals. Most of the traits to be represented were distributed between physical (14) or a behaviour property (4) and the selection pressure were represented as either an external enemy (in 12 cases) or environmental causes (like lack of food, 8 cases, Table 2). In two of the animations, it was not possible to detect any selection taking place. External enemy 12 Lac of accessible food 8

Multimodal resources utilized in student generated stop-motion animations
The students utilized the resources which had been made available to them by the media educators. All student groups used clay as basic material, but it was supplemented in various ways by paper and drawings. Some groups added thread, nails, stone, and wood shavings, and in one of the animations, Lego. In addition to the visual material mentioned above, the students added other modalities. *An animation may contain more than one addition to the animation. Some sort of audio or text was added to all stop-motion animations except one. Of these, sound effects and music were more common than read text. Four of the stop-motion animations included written text, either directly or in speech bubbles. In fact, one animation included all four (vilka?) of these media (see Table 4). By the use of bubbles, drastic sound and sometimes also speech, these multimodal expressions contributed to make the animations funny. All design features of the student generated animations are summarized in Table 4. The most remarkable result was the difference regarding the alternative conceptions. Intentionality was somewhat less common in the stop-motion animations, and essentialism was shown in only one of the animations. However, the natural selection represented as a single event was almost four time as common in the animations compared to the written responses.
Connections between organizational levels are about similar (20-30%) in the animations as in the written responses, while connection between different tempo aspects of the process is about twice as common in the written responses (60%) compared to the animations (33%).

Key concepts
Individual variation in the animations are shown in two different ways: 1) Most often only one individual with a different characteristic is shown, e.g. camou age or ability to jump, making it more a variation of a type (Zabel & Gropengiesser, 2011). 2) More seldom several individuals had different properties ( Figure   6). The decision to make simple models allowed the group that made the organisms with different body sizes ( Figure 3, left panel) to generate a larger population than the group who made realistic giraffes with differences in neck-length ( Figure 3, right panel).
Differential survival (E4) is represented in various ways in the stop-motion animations. In most cases a population of a pray species varies. Diverse traits are represented in the animations, including long legs, ability to bounce, spikes, or spots that help evasion from a predator. Given that the medium is visual, the students had to think about traits that would be easy to visualize. Consequently, most of variations are morphological or visual, such as difference in camou age, length of legs or neck, or body size. In a few animations the survivors have superior cognitive properties than other members of their population, such as greater smartness or cooperation skills. The represented selection pressure is generally predation or lack of food (in 12 and 8 cases respectively). In one animation environmental change divide populations and introduce differences in selection pressures in the environments. In two cases both predation and food limitation are illustrated. In ve cases a predator varied and becomes a better hunter ( Table 2).
In one case the story is more complex, with selection affecting both prey and predator populations, in a valley divided by a stream (Figure 6). The valley is populated with symbolic animals in the form of balls of varying size. Food is plentiful on one side of the stream and scarce on the other. Food shortage causes death of the larger prey individuals on the barren side, while on the rich side of the valley they thrive and avoid being eaten due to their size. Hence, the predators starve on the fertile side of the stream but thrive on the barren side.
In the student generated stop-motion animations the animated populations are generally very small, which makes it di cult to judge Change in population (E5). However, if we consider the "initial population" as a group of more than three individuals, this concept was represented in nine of the animations. Further, the variation in this population is most often limited to two variants, of which one is bene cial. In other words, the random variation in the original population is missing. In addition, after selection the change in the population in most cases happened momentously or after one to three generations. The accumulation of changes is not represented.

Alternative conceptions
From a science education perspective, it is easy to discern an anthropomorphic touch, as a represented organism has (as in this example) human-like self-awareness. Other displays of anthropomorphism include animals using weapons, living in houses, or wearing clothes. However, although these displays were not coded as intentional, they are easier to attribute to a pure aesthetic style rather than a representation of design based on intentions (Kampourakis, 2020).
Intentionality (A1) as a basis for selection were illustrated in seven animations (Table 3). One animation was showing a mammal adopting to life in the water in a process of metamorphosis (animation 6), and one with the theme of evolution of man ( Figure 5, animation 7). The students who produced these animations seemed more focused on providing a historical description of the changes in a species rather than the mechanism responsible for the changes. Representing evolution as a process that is goaldirected, striving upwards or at least onwards (into the sea), is a typical expression of teleology. These animations have in common that they do not show any variation. One individual undergoes morphological development to be more man-like (Figure 7) or able to swim in the sea.
Earlier research have pointed out that essentialism is a major alternative conception (Coley & Tanner, 2015). Surprisingly, essentialism (A2) was only manifested in one animation ( Figure 3, right panel) in which the necks of all giraffes grow (after that the individual with the shortest neck has died). However, the two examples above, the dolphin and the march towards man, might be interpreted as showing an essentialist evolution if the individual is assumed to represent the evolving essence of a population. This is not in line with our de nition, so they were not included in this category.
However, evidence of the alternative conception natural selection as an event (A3) was detected in 14 of the animations (Figure 2 a). The animation in Figure 8 provides a good example. Either you have good camou age, or you don't, and in that case, you get eaten. The one survivor in this animation gets the jackpot of opportunities to mate and reproduce (Figure 8).

Connections in organizational levels and time
With connection between different organizational levels, we mean that students can link genetic variation to individual variation and/or individual variation to population level. Only one animation includes genetic level, while nine animations show individual and population level.
Most substantial changes of traits in populations take long times and involve many generations (although some traits may become xed in a single generation under intense selection pressure). The time or generations passing, was indicated in six (33%) of the animations (Figure 2 a). Time was indicated by e.g., by mating in one to three generations, or in text (for example "many generations later"), alternatively by the sun or moon rising and setting, or the earth spinning (Table 3). Table 3.

Discussion
The theory of natural selection is challenging for learners, and their potential alternative conceptions are reportedly di cult to change (Chi, 2005;Coley & Tanner, 2015). However, previous ndings indicate that changes in, for example, the context of a test item may lead students to focus on different key concepts in their answers (Göransson et al., 2020;Nehm & Ha, 2011). Further, results from text-and spoken language-based tests indicate that changes in test items' formulation can alter the propensity of many students' who hold alternative conceptions of evolution through natural selection to agree with teleological, anthropomorphic, and essentialist statements (Gouvea & Simon, 2018). Our study explores this issue from a different angle, by investigating how changing the test medium (here from pen and paper to creation of stop-motion animations) in uences what students express. Our results show that (with our setting, context, participants, and format), the differences were mainly connected to the alternative concepts.

Stop-motion animations reveal a different pattern of alternative conceptions
Many studies have found that students tend to use explanations based on intentions, for example that changes occur in direct response to a new selective pressure or need (Ware & Gelman, 2014) or that changes are induced by the environment or the 'feelings' or 'will' of the species (Harms & Reiss, 2019). These investigations are exclusively based on responses to written items. Our results indicate that representations of the alternative concepts in collaboratively generated student stop-motion animations differ compared to what has been detected in individually written responses ( Figure 2 a and b).
We found that students expressed essentialist ideas relatively frequently in their written explanations of natural selection, but rarely in the animations. Furthermore, we found that ideas of intentionality were expressed less often in the stop-motion animations than in the written responses ( Figure 2 a and b). This may be an effect of the medium. However, another potentially important factor is that the depictive representation of an animation can be more analogous to the represented process (Schnotz, 2002).
In addition, many students might lack the adequate scienti c language, and their explanation of concepts and processes might in some cases have been considered as alternative explanations. Words like adaptation and selection appear both in everyday language (in Swedish) and in biology (Bishop & Anderson, 1990) We suggest that in many cases the descriptive representational mode of writing is ill-suited for representing the complex processes of natural selection and changes in populations. These limitations lead students to use formulations that are not consistent with strict scienti c formulations. This nding might be very important and support further research on the use of alternative methods, as for example student generated stop-motion animations, for helping the students to express their knowledge.
Further, stop-motion animations appear to invite to describe natural selection as an Event (A3). Almost 2/3 of the stop-motion animations indicated that the selection process was as an event (in one or very few generations) (Figure 2 a). We do not know the students' intentions. It requires less effort to produce models of a few generations than a thousand. However, we argue that in many cases this should not to be seen as a re ection of students' conceptions but an effect of constraints associated with the method are not used to representing ideas in that type of medium (Farrokhnia et al., 2020). This impression is reinforced by the fact that only four groups created a population that contain more than four individuals.
Time might not be enough to make many individuals if they chose to make realistic animals. This assumption is also supported by that the four groups who did a population made simpli ed models (e.g., Figure 3 left, Figure 4 right, and Figure 6).

Character of the alternative conceptions
Regardless of the causes behind the different patterns in the expression of the alternative conceptions, our results are di cult to explain based on the idea of conceptual frameworks, as suggested for instance by Coley and Tanner (2015). Together with other studies which have indicated that context, and speci c tasks affect what conceptions students display (Göransson et al., 2020;Nehm et al., 2012), the analysis of the collaboratively student-generated animations in this study support that so-called alternative conceptions to a high degree stem from students' context-speci c interpretations of each task rather than cognitive frameworks (Gouvea & Simon, 2018 Linking different organizational levels Only one stop-motion animation managed to link origin of variation to individual variation. This was also seldom represented in the written explanation. The reason for this can be that the origin of the individual variation was something the students did not think of when they planned the animations ( The connection between individual change and change in a population was shown somewhat more frequently (in four of 18 animations). It is simpler to generate several animals than to connect to change in genes, but on the other hand, the time limitation of the session might explain the low number of connections between individual to population.
Stop-motion animations do not appear to be superior to written responses to show students connections between organizational levels and time frames. In the written responses more than half of the student´s mention time dimension of evolution and time was often quanti ed by saying that e.g. "after a lot of generations" or "after thousands of years" the cheetals had develop running capacity. In the animations the time dimension was less commonly illustrated, in particular it appeared to be di cult to show how much time evolution through natural selection takes. However, students who aimed to show time often use creative solutions invent some symbolic representation of time. Table 3 show that students bring different resources for handling dimensions of time to the classroom. In a few of the animations, a narrator, (and to lesser extent text or arrows) provide explanations stating that, for example, "time is passing", or "mutations are happening". Thus, both animation and sound or written texts contribute to communicate these concepts and strengthen the argument that multimedia representations can help students express their conceptions.
If methods for eliciting the need of expressing non-perceptual size and time had been included in the teaching sequence (McLure, Won, & Treagust, 2020), then perhaps the relationships between the levels of organisation and magnitudes of time would have been emphasised more in the animations.

Plant blindness
The students had clearly ideas about the concepts of natural selection, and when given the opportunity to use their creativity in stop-motion animations we observed great diversity in their expressions. However, in one way the animations were similar -they all illustrated ENS with animal examples.
Identi able animals such as dogs, humans, shes, and turtles were used in most of the animations. We suspect that in the minds of students that produced these animations, evolutionary change is more strongly connected with animals than plants, and/or it is more fun to make an animation with something that moves around a bit. This might be explained with that animals are usually used in education to illustrate evolution This nding can also point to the phenomenon of plant blindness (Wandersee & Schussler, 1999), where plant life is simply not noticed. That learners ignores the important ecological role of 80% of the biomass on earth have raised calls for giving plants a greater role in biology education on all levels (Jose, Wu, & Kamoun, 2019). However, this is in our opinion a mistake, leading to a that students do not understand evolution as an all-encompassing model of life development. Furthermore, this reinforces a need to expose learners for ENS in other contexts than animals (Pugh et al., 2014). For example, Göransson et al. (2020) show that changing to a bacteria context, lead students to focus the origin of variation and the micro-levels of organisation.
A few groups (four) used a more schematic simpli ed "animal", which might indicate higher representational competence (Ainsworth et al., 2011), through use of a simple model to explain a principle rather than a concreate realistic example. An alternative possibility is that using simpli ed "animals" re ects low self-con dence in making gures with clay or simply taking the easy way out.
Either way, the more schematic organisms generally allowed the students to work with somewhat larger populations.

Stop-motion animations induces creativity
The majority of the students appreciated the experience and experienced the making a stop-motion animation as a rare opportunity to use their creativity in biology education (Bruna, 2013). An effect of the intended audience being peers in a parallel class may possibly have been that the students rather reinforced the entertainment value of the animation at the expense of giving a clear explanation for evolutionary change (Nielsen et al., 2020). For instance, music and sound effects seemed to be important to the students, as almost all animations included some, but it appeared in many cases to be for purely aesthetic reasons rather than contribute to the explanatory value. The ideas were in many cases taken from popular culture, like the march towards man trope, as well as evolution like in the Pokémon games. Several groups attempted to twist the narratives from classical ones like an animal climbs out of the ocean and start walking on land was turned around to be the story about how an animal on land started swimming in the ocean and got ippers instead of legs. Other groups kept to the example from the biology textbook, showing how the giraffes got long necks. The animations also provided more opportunities for humorous expressions and exploring odd ideas, like a bird feeding by falling and hitting its prey in the 'head'. The predators were often made horrible and scary and a predator attack was dramatized with visualized attempts of prey to escape. Overall, 89% of the animations contained some humorous detail, often towards the end of the animation.

Conclusions
Our study highlights some of the bene ts and limitations of using collaboratively generated stop-motion animations and open written response tests for probing students' understanding of evolution through natural selection.
In comparison to written responses collaboratively student-generated stop-motion animations did … … effectively have the same pattern of key-concepts, except for origin of variation …more commonly express natural selection described as an event.
…more seldom show …increase creativity, humor, and engagement. …make students to use different modalities to illustrate time.
However, they did not… …help the students to connect organizational levels.
…help students to students to quantify the time dimensions of the process.
At the same time, creating stop-motion animations is a time-consuming technique made the students take shortcuts and accelerate their storytelling in at least the following three ways.
They did not make large populations. Instead, most of them represented variation in a few individuals.
They did not make nice displays of gradual change of populations, but rather a few individuals, in most cases only one individual, had a changed trait.
The numbers of generations/amount of time required for change in the populations was very rarely shown. Instead, changes in the represented populations usually occurred in a fast, event-like manner.