Abstract

Evolutionary trees communicate both the diversity and unity of life, a central and important scientific concept, as highlighted by the Vision and Change undergraduate biology education movement. Evolutionary trees and cladograms are diagrams viewed by biologists as Rosetta Stone-like in how well they convey an enormous amount of information with clarity and precision. However, the majority of undergraduates in introductory biology courses find the non-linear diagram confusing and do not immediately understand the tree-thinking central to interpreting the evolutionary tree’s branching structure. Go Extinct! is an original board game featuring land vertebrates (i.e., amphibians, mammals, birds and reptiles) and it is designed to engage students in reading this evolutionary tree. Go Extinct! won the Society for the Study of Evolution’s Huxley Award for outstanding outreach achievements in recognition for how the gameplay itself incentivizes students to identify clades and common ancestors on a stylized tree. The game can be completed in about 30 minutes, which allows instructors time to give follow-up activity sheets that help students transfer their new ability to read a stylized tree into the ability to read more traditional-looking trees found in textbooks and the literature. Overall, teaching the game, playing the game, and completing the follow-up transfer activity can be completed in a 50-minute section. Each game can serve up to 6 students, which means 3 games can cover a section of 18 students. Go Extinct! provides a fun and effective learning experience that students will remember and may even request to play again.

Primary Image: Biologists play Go Extinct! Students who play Go Extinct! gain a mastery of reading an evolutionary tree or cladogram. The winning strategy depends on identifying common ancestors of animal cards in your hand. Photo taken by the author.

Citation

Lesson Learning Goals

• read an evolutionary tree, identifying monophyletic clades and common ancestors.
• understand that multiple sources of evidence can be used to build an evolutionary tree.
• discover surprising evolutionary relationships between well-known animals. For example, chickens are dinosaurs.

Lesson Learning Objectives

• read an evolutionary tree (i.e., a cladogram) and transfer the skills they learned from playing the game to more traditional-looking trees found in the literature.
• apply tree-thinking to identify common ancestors and articulate how the tree structure represents some animals as more closely related than others.
• identify the heritable traits that scientists use as evidence to infer the degree of relatedness between species and build a cladogram. Evidence includes DNA, skeletal anatomy, and reproductive habits.

Introduction

“Nothing in biology makes sense except in the light of evolution” as Theodosius Dobzhansky famously stated in the American Biology Teacher (1). More recently, the 2011 Vision and Change report lists evolution as the first core concept that students must master in order to become biologically literate (2). If evolution is the unifying theory of biology then evolutionary trees illustrate key concepts such as common ancestry, heritable traits, and degrees of relatedness (3). Indeed, biology practitioners could even say that they use evolutionary trees like Rosetta Stones: diagrams that concisely compare and contrast the evolutionary paths of different yet related species. For example, experts often use evolutionary trees to succinctly communicate relationships among organisms (4). These diagrams can concisely communicate complex evolutionary ideas, including whether traits are inherited from common ancestry or arise from convergent evolution.

The ability to understand evolutionary trees as displays of evolutionary relationships is termed “tree-thinking” (3, 5). It is well-documented that most undergraduate students enter introductory courses without tree-thinking skills (4, 6–8), rendering evolutionary tree less like insightful Rosetta Stones and more like confounding rat’s nests. This lesson was inspired by challenges faced by a diverse cohort of students in Stanford’s interdisciplinary human biology introductory course (9). I found that linear formats such as lectures, reading, and office hour sessions at the whiteboard were often not adequate, time-consuming, and frustrating for students who felt stuck. Designing a board game about tree-thinking became my solution, because games are inherently non-linear, and they provide an approachable way to practice a challenging skill. My original board game, Go Extinct!, centers around gameplay that organically facilitates tree-thinking (Figure 1). I also provide pre- and post-game worksheets to ensure that students can apply the skills they learn from the game to more conventional-looking displays of evolutionary trees (e.g., 10).

Go Extinct! won the Society for the Study of Evolution’s Huxley Award for outstanding outreach achievements and has been featured in Science (11) and Nature (12). Go Extinct! plays similarly to Go Fish (also called Happy Families) and can be played by students as young as 8 years old (13). This means undergraduates learn the rules quickly. Instead of completing pairs of cards as in Go Fish, students playing Go Extinct! seek to collect all of the animals in monophyletic crown clades, shown with color-coding on the board. To complete these sets, students must focus on the evolutionary tree and apply the new rule that allows them to ask for animal cards within any clade on the board. In this way, the game leverages its medium by motivating players to critically examine the evolutionary tree on every turn (13). Students also get to sling a cheeky “Go Extinct!” at opponents when they do not have any of the desired cards to give! Because students win the game by completing the most monophyletic crown clades, asking for deeper, more inclusive clades improves their chance of getting a useful card from an opponent. Therefore, students who can identify common ancestors among two or more cards already within their hand tend to find success at completing monophyletic sets. The winning strategy incentivized by Go Extinct! thus motivates students to apply both probability and foundational tree-thinking skills (5, 8).

While gameplay actively engages students in the hierarchical, nested nature of evolutionary trees, the game’s content highlights the key adaptations that allowed fish to colonize the land. The focus on land vertebrates allows instructors to point out how their evolutionary tree reflects the natural history of adaptations to move, eat, and reproduce without a watery environment. Indeed, the nicknames that identify common ancestors often highlight inherited traits that dramatically increased success on land, such as the shells of amniotic eggs (14), the tooth sockets in archosaur mouths (15), and the long pregnancies of placental mammals (16) (Table 1). Instructors can use these adaptations to connect concepts from microevolution to macroevolution, namely how the structure of the evolutionary tree reflects the adaptations that evolved in each lineage (17). The trait icons also highlight the variety of evidence that biologists can use to build evolutionary trees. Evidence featured in the game includes physical traits, reproductive traits, DNA sequence similarity, and the location of fossils. Table 1 provides a detailed explanation for how each clade’s nickname can prompt a conversation about adaptation and/or scientific evidence behind the tree (e.g., “Shell Shockers” for the shocking amount of diversity facilitated by the amniotic egg [14]). Finally, instructors can engage students in evolutionary stories illustrated by the board, including convergent evolution—such as powered flight, bipedal stance, and limb loss. This last trait can prompt a conversation about what happens when a four-limbed tetrapod, such as a snake or a whale loses limbs (i.e., it is still technically a tetrapod and its embryonic development reflects this four-limbed history [18, 19]). Therefore, as students practice tree-thinking, Go Extinct! scaffolds evolutionary discussions supported by a tree of familiar organisms.

Table 1. Evolutionary Talking Points. Go Extinct! illustrates many key evolutionary concepts through land vertebrate natural history. This table provides a partial list of evolutionary concepts that can be discussed during gameplay with student groups as you circulate the room.

Compared to conventional class activities, games are known to motivate students as well as to improve learning and retention of material through peer learning and the repetitive cycle of turns that provide immediate feedback (20–22). Games tend to be popular and can engage students who may be less motivated by more traditional class activities, in some cases empowering these students to teach their peers. CourseSource has published several game-based lessons, including an introduction to evolutionary trees through the lens of life-history strategies (23), an evolution misconceptions game show quiz (24), and an exploration of algal diversity through a sorting game and a build-a-tree activity (25). Build-a-tree activities have been shown to be more effective in teaching tree-thinking than activities like Go Extinct! that analyze existing trees (26). However, I found that many undergraduates in introductory courses often require more basic familiarity with evolutionary trees before having the efficacy needed to build a tree from a trait matrix. Therefore, Go Extinct! can serve as a necessary primer on tree-thinking that sets students up for success with subsequent build-a-tree activities, such as lessons existing on CourseSource for algae (26) and Crassulaceae plants (27).

In summary, Go Extinct! successfully teaches students how to read and apply evolutionary trees for three main reasons:

1. The winning strategy and the learning goal are inextricable. The game’s most important action, which students perform on every turn, is asking for a card by specifying which clade the animal should come from. Over the course of the game, students are rewarded for thinking critically about how a clade’s inclusivity impacts their probability of getting the animals they need. This makes for tangible and memorable practice with tree-thinking.

2. Students make meaningful choices every single turn. There are many variations on the winning strategy and there are no wrong asks (just slightly less effective ones). Having meaningful choices both increases engagement and creates a sense of agency and ownership over their developing strategy. As all teachers know, if you can prompt students to make connections on their own, they are far more likely to remember the concept or skill than if connections are made for them. They are also likely to feel empowered to learn more.

3. The activity is highly social, active, and, most importantly, fun. A game is a set of rules that, when set into motion by players, creates a dynamic system that inspires an internal narrative in each player about what is happening (28). In other words, games are systems that happen to be fun. As science teachers, we are often teaching our students about systems or systems-thinking. The social aspect of the game allows students to learn from their peers through observation or because certain students feel empowered to explain the parts they have mastered. The fun aspect—created through social interactions and each student’s internal narrative of the game—fuels engagement and builds positive associations with evolutionary trees.

Intended Audience

This lesson is designed for majors or non-majors in introductory biology undergraduate sections at the university level. This activity is also suitable for high school students learning macroevolution. The course content focuses on the evolutionary relationships among land vertebrates.

Required Learning Time

The lesson is designed for a 50-minute section activity.

Prerequisite Student Knowledge

This activity is designed so that students with little to no prior knowledge of biology or evolution can understand and engage with an evolutionary tree. The game features many familiar land vertebrates, which serve as an accessible entry point for reading the evolutionary tree. Many students will be familiar with the general structure of the tree that sets up amphibians, mammals, birds and reptiles as the major groups of land vertebrates. Most of the animals featured in the game, such as frogs, lions, mice, etc. will be well known to students and this will support students in identifying the evidence used to build the evolutionary tree.

Prerequisite Teacher Knowledge

To present this activity, instructors must possess a solid understanding of evolutionary trees and the tree-thinking required to identify common ancestors and to infer relatedness between animals on two different branches. Furthermore, the game features the specific evolutionary tree of land vertebrates and evidence used to build a cladogram among these animals. It would be beneficial to instructors to have some familiarity with the heritable traits that are often used to group the land vertebrates into clades. These traits—such as laying eggs, having teeth in sockets, or long pregnancies—often reflect the challenge of fish attempting to live, eat, and reproduce on land, without water. Having this lens on the tetrapod macroevolutionary story can connect the tree to the microevolutionary events of adaptation to land. This Scientific American article gives a useful overview of the tetrapod story through this lens (17). Finally, to conduct the game activity, the instructor should be comfortable with the rules, which are very similar to Go Fish (also called Happy Families).

Scientific Teaching Themes

Active Learning

This lesson engages students through gameplay, a rigorously scaffolded group activity, and through worksheets—all are active learning techniques shown to accelerate learning for undergraduates (29, 30). Games in particular are known to improve learning outcomes because players engage in a cycle of making judgements, receiving feedback, and altering behavior accordingly (20). Games effectively ensure that all students remain motivated and engaged in the group work because, as players, they must actively assess the game system and the choices of their peers (21). Compared to conventional teaching methods, serious games have been shown to improve learning and retention, an outcome that was improved further by the inclusion of a follow-up worksheet (22). Therefore, this lesson aims to engage students in active learning for the majority of class time, which has been shown to increase student achievement and success in STEM (31).

Assessment

Gameplay provides students with immediate feedback, and points scored in the game reflect relative mastery of the learning objective to read an evolutionary tree. The follow-up worksheet will allow students to self-evaluate whether they can transfer the skills learned from the game to more conventional-looking trees. Students will also be able to self-evaluate the progress made relative to the worksheet they completed before class. The follow-up worksheet will allow instructors to assess how well students transferred skills practiced on the stylized tree in the game to more conventional evolutionary trees.

Inclusive Teaching

Games afford multiple ways for students to participate and to learn from their peers. Often, games provide an alternative learning format that engages students with non-traditional learning backgrounds who then get to be experts on the game among their peers. The game itself is designed to communicate information in more than one way, for example, clades are identified by color, an icon highlighting the evidence unifying the clade, and a nickname that highlights a common trait. In this way, the game follows guidelines from the Universal Design for Learning (32). Most of the lesson features group work, so that the instructor can circulate and converse with students one-on-one and in small groups to ensure that all members of the class are included in the lesson and understand the activity.

Lesson Plan

A recommended timeline for this lesson is summarized in Table 2.

Table 2. Lesson Timeline. Creating the games can be time consuming, but once they are made, Go Extinct! engages students in tree-thinking for the majority of the 50-minute session.

Pre-class Preparation

Game Preparation

Preparing the game involves printing and cutting out the cards (Supporting File S1) and board (Supporting File S2) (see Table 3 for further instructions), and doing so for enough game sets as required by your largest section of students. Each game can serve 3 to 6 students so that the number of games needed can be found by dividing your class size by 6 and rounding up to the nearest whole number (e.g., 22 students / 6 = 4 game sets minimum required). Each game set consists of 54 cards and an evolutionary tree board. Completing 4 game sets will take about 1–2 hours to create, depending on how sturdy you decide to make the sets (e.g., lamination). Alternatively, production quality games can be purchased from Flinn Scientific (while supplies last; see STEAM Galaxy Studios for alternative options).

Table 3. Printing instructions for materials needed in the lesson.

The cards should be printed in color and double-sided so that the back design blocks the color of the face, thus removing the temptation to cheat! Standard quality paper will work but heavier cardstock, such as that offered by a standard copy and print shop, will last longer. You may also consider laminating the cards before cutting them out as another option (or addition) that will increase the longevity of your games for future lessons. Cut the cards along the lines of the back design such that they are all roughly the same standard playing card size. Shuffle the deck thoroughly before handing out to the students as this is important for the game to function well.

The board should be printed in color and single-sided. Standard quality paper works well because the board is handled less, however, heaver stock will increase longevity. The board is meant to be tiled together from the six pages; therefore, cut off the white margin, leaving only the blue part. Tape the pages together by matching the design of the tree across pages so that duplicated parts of the tree are hidden. Store the board by carefully folding the final product. Alternatively, use a print and copy shop to print the entire board in full (Supporting File S3).

Printing out the Rulebook (Supporting File S4) for each set is optional, especially if you assign the PDF as required reading before class.

Be sure to familiarize yourself with the rules of the game by playing it with at least two other people before the lesson. The rules are also thoroughly explained in the lesson PowerPoint (Supporting File S5), both on the slides and in the presenter notes. You may find it helpful to watch the rules explanation in this YouTube video (1:30 through 5:58).

Worksheet Preparation

Be sure to assign the pre-lesson worksheet (Supporting File S6) ahead of class time. Answers to the worksheet are provided (Supporting File S7). Ask students to bring their completed worksheet to class, as this is helpful to compare to the post lesson worksheet (Supporting File S8) that they will complete in groups after playing the game. Answers to this worksheet are also provided (Supporting File S9).

Be sure to print out one post-game worksheet for each student, double-sided on standard quality paper.

Classroom Preparation

Games are best played when students can sit facing one another. If your classroom is not already set up in pods, move the desks so that students can sit opposite one another. Provide at least the board at each table so students can reference it during the beginning rules explanation. Providing cards can become distracting for students so that it may be best to hand these out after the rules explanation has finished.

While not ideal, Go Extinct! games can be played in a traditional lecture halls with tiered seating and retractable desks. I recommend asking students to arrange themselves in groups of five with three students above the other two students in the row below. This way each student can turn to face the others without their cards being shown. I also recommend printing an extra board so that both tiers of students can see and refer to it. The boards can be placed on the desks with the draw pile on the lower section of board, in a blank space not overlapping the tree.

In-Class Plan

Game Pitch and Rules

After welcoming students to class, launch into the first four slides of the PowerPoint that introduce and “hype” the game. These slides are designed to provide students with enough context to feel like this game will be easy to learn yet fun to play, all while practicing a difficult skill. Games are generally appealing to students, but some students may balk at the competition factor. While hyping the game, be sure to emphasize the friendly nature of this competition. For example, “Go Extinct!” is meant as a silly insult that scientists might sling at each other. You might also emphasize the close similarity in gameplay to Go Fish, a game with which most students are very familiar. The presenter notes in the slides (Supporting File S5) provide word-for-word suggestions for dialogue that emphasizes the accessibility and value of Go Extinct! as a game teaching an important and difficult skill. Make sure students understand that color communicates relatedness as this will scaffold them in reading the tree during the game. Note that reading an evolutionary tree without this color-coding is what the post-game worksheet will help students to do.

The next five slides go through the rules in detail. Again, the presenter slides (Supporting File S5) contain word-for-word dialogue known to convey the rules well enough for students to start playing on their own. Make sure students understand the asking rules and that they can ask for any one animal from any clade on the tree. For example, if they need a Chicken, then they can ask for it directly or ask for any clade to which the Chicken belongs, e.g., Terrible Lizards (Dinosaurs) or Toothy Grinners (Archosaurs) or even 4-Legs (Tetrapods). If they also need a Chameleon, then both animals are Holey Heads (Diapsids), making the ask for this common ancestor a good strategy (Figure 2). Explain the Ask Again rule, which makes the game competitive and incentivizes thoughtful asking strategies. Explain the Declare and Reset actions briefly as students will pick these rules up during play. Make sure to conclude by telling students to ask you for the rule change that occurs once their draw pile runs out.

Gameplay

Leave slide 10 up on the projector for students to refer to as they begin play. Hand out the decks of cards and ask students to shuffle them thoroughly. Circulate the room and clarify rules as needed. Once they understand the rules, students will be independent and self-contained in this activity. The room may get loud, but this is normal for gameplay. At each table, you can interject with comments about evolutionary trees or the natural history of vertebrates, as you deem appropriate. Table 1 provides a list of potential talking points for each clade in the game, but these are optional as the learning objectives will be completed through students playing the game.

Once the first group runs out of their draw pile, switch to slide 11 and explain the End Game Rule, namely, that students must give up to three cards in a clade instead of just one. This rule speeds up the game and gives players who are behind a chance to catch up! Once the game is complete, encourage players to count up their points and congratulate the winner. If there is time, ask students to articulate their strategy.

Post-Game Worksheet

Hand out the post-game worksheet (Supporting File S8) to groups who have finished the game. This worksheet is necessary for students to apply the tree-thinking skills they practiced in the game to more standard-looking evolutionary trees or cladograms. The last question is intended to be difficult and students are encouraged to return to the pre-game worksheet (Supporting File S6) and discuss the questions as a group. I recommend uploading the answers to both worksheets to the course website and/or going through the answers in the following class period. Both worksheets can be used as formative assessments and I recommend collecting them from students at the end of the class period to assess how well they transferred skills from the game onto related biological concepts. The three drawing exercises on pages one and two will test whether students can convert the colorful evolutionary tree featured in Go Extinct! into more traditional representations of clades. The last drawing questions test whether they understand how clades can be collapsed into more simplified trees. The final drawing question concerning the evolution of flight is difficult, and I recommend engaging with groups of students to scaffold them in answering this question. The rakali questions on page one test whether students understand the evidence used to group clades together, and these questions tie in how evolutionary trees are used in research.

Teaching Discussion

Go Extinct! is a fun and effective activity that teaches tree-thinking, a persistently difficult concept (3). While quantitative data on the game’s effectiveness do not yet exist, this Discussion presents the qualitative perceptions, testimonies, and experiences of myself, fellow instructors, and professional societies who have used the game to teach. I have used the game successfully in the US and Australia with undergraduates—both majors and non-majors—high school students, homeschooled students aged 8 and up, and even masters students in inclusive education. I found success in engaging a wide range of students and in improving student confidence with evolutionary trees. Excitingly, even middle school students could articulate the definition of a clade and the fact that clades can be big or small after playing one round of Go Extinct! Thus, although tree-thinking is a skill normally taught in secondary and undergraduate contexts, it is accessible to younger students with the right scaffolding. Go Extinct! provides such a scaffold for all players to learn rigorous tree-thinking skills. This lesson provides two forms of formative assessment, which will allow instructors to assess whether their students are ready for more challenging activities on related concepts, such as phylogenetics and building a cladogram from a trait table (e.g., 22, 25, 26). Go Extinct! is Next Generation Science Standards aligned (Supporting File S10) (33).

Go Extinct! Levels Up Student Engagement

The game format provides many advantages, including a social context where students can learn from one another; a low-risk setting where experimentation and learning from mistakes is rewarded; a competitive challenge where students make meaningful choices informed by the evolutionary tree; and finally, an activity where they receive immediate feedback on their decisions (34, 35). For all student grade levels, I observed that virtually all students stayed engaged in the lesson with a majority of students stating that they enjoyed the game and would play it again. I know of at least three other instructors who reported students requesting to play the game again during another section or even during their free time.

Furthermore, virtually all students could answer the first two cladogram drawing questions on the post-game worksheet, meaning that they are likely able to transfer the tree-thinking practiced in the game to more traditional looking cladograms and evolutionary trees. The majority of student groups could answer the post-game worksheet question about the evolutionary position of the Australian rakali, demonstrating an understanding of the evidence used to construct evolutionary trees. Students struggle the most with the last cladogram drawing question on the evolution of flight, but with some instructor assistance, most groups can answer it correctly. This illustrates an understanding of how cladograms can be used to portray different combinations of organisms and support different research questions.

Professional Praise for Go Extinct!

In addition to the Thomas Henry Huxley Award for outstanding evolution outreach achievements, Go Extinct! won recognition for effective and inventive game design at the 2016 IndieCade Festival, known as the “Sundance Festival” for independent game designers. Game reviewers at Georgetown University noted that “despite the straightforward gameplay, strategies quickly begin to emerge, as each player tried to avoid revealing what they held while carefully listening to what is said in order to seek out desired cards.” Furthermore, multiple national teaching organizations have also reviewed Go Extinct! including:

“We were pleased to find the contents hilarious... By the end, everybody knew what a clade was: a concept that seems to elude many undergraduates.” – Dr. Emily Schoerning, National Center for Science Education

“It’s so important that our students see the relatedness of living things like the branches of a tree. This game helps them visualize phylogenetics in a fun way, dispelling common misconceptions about evolution being a ladder of progress.” – Bertha Vazquez, Director of the Teacher Institute for Evolutionary Science

“Go Extinct! is a fantastic science game that should be on the shelves of every middle school science classroom! The game is easy to play with colorful illustrations and excellent science facts that take playing and learning and integrate them into one unique experience.” – Emily Waisanen, National Science Teachers Association

In summary, I have found in my teaching and from the feedback of a diverse set of instructors that the game successfully introduces the skill of reading evolutionary trees. Importantly, it does so in a uniquely memorable fashion. While the skills practiced in reading a colorful game board need to be transferred to more traditional representations of evolutionary trees, this is the role of this lesson’s bookending worksheets. By the end of the 50 minute class period, students feel capable of reading cladograms and identifying monophyletic clades on the types of evolutionary trees found in textbooks, other lessons, and some scientific articles. These foundational skills can support more challenging phylogenetics activities by grounding students in tree-thinking basics. Games can be a time-consuming activity; however, the central importance of evolution in all science standards warrants the teaching time and effort to convey these concepts. Both the Next Generation Science Standards and AAAS’s Vision and Change report emphasize evolution (2, 33), therefore it is well worth the time to ensure that all students feel grounded in the basics and excited about using evolutionary trees.

Notes on Accessibility and Inclusion

Educational board games can be effective and inclusive teaching tools that benefit a diversity of students (22, 36–38). Indeed, board game activities closely resemble collaborative learning, which is an educational approach involving small groups of students participating on a collective task that has been clearly assigned (39). Collaborative learning has a wealth of literature supporting the benefits of this method on a diverse cohorts of students, including ethnicity, gender, and skill levels (40–42). Games have been shown as beneficial for students on the autism spectrum, partly because social interactions are highly organized with clear rules of engagement and partly because mastering the game’s strategy often plays to their strengths (43). To my knowledge, at least one educator has successfully used Go Extinct! with a small group that included students on the spectrum and those not on the spectrum.

Go Extinct! is an inclusive activity because everyone gets their turn to make choices and complete actions. Indeed, the game only works when turns are shared, and everyone plays fairly. Games reach students with different learning styles by providing multiple routes to understanding (44). There are many ways to explain how to read evolutionary trees and Go Extinct! allows students the opportunity to find the way that makes the most sense to them through play. Importantly, the feelings of agency that come with discovering a successful tree-thinking strategy are empowering, memorable, and fun. Paleontologist Taormina Lepore said, “This board game is a science teacher’s dream...In five minutes I had my least motivated kids in class teaching my dinosaur nerd how to play, while all the students involved got excited about collecting clades...Their test scores improved, too.” The social aspect of games will engage extroverts, while introverts tend to be very good at listening and will enjoy this as a strategic advantage (45). Regardless of personality type or learning style, Go Extinct! allows every player to develop their own strategy in an activity where repetition is expected and enjoyed.

Go Extinct! uses color to reinforce the degree of relatedness between the animals on the board. The collectable clade sets are color-coded but students with color blindness can always rely on the unique icons in the top left corner of each card and the clade nickname in large font. While no further accommodations are needed for color blindness, all students experience color differently and some may perceive the red-purple colors of the Warm Fuzzy clades to be very close. Therefore, I recommend telling all students that the icons and clade names are complementary to the color-coding.

Similar to other card games, Go Extinct! involves holding a hand of 1–9 cards, taking the top card from a deck, and passing specific cards to specific opponents. If a student has a disability that impacts the fine motor control needed to play, plan for another educator to perform these small tasks on the student’s behalf. The educator should only act on the silent cues received from the student, such as which card to pass to an opponent. Fine motor skills are not required for students to get the full benefit from listening, making decisions, and forming their own gameplay strategy.

Formative Assessment is Built into Go Extinct!

Games can be a form of formative assessment (46), notably including card games in a science context (47) and competitive games in a biological context (48). By playing games within groups, educational card games provide an environment where students learn from peers, which boosts the acquisition of knowledge (49, 50). In Go Extinct!, the winning player is usually the person who became best at leveraging the evolutionary tree to increase their probability of getting the cards that they need. Students gain this insight usually from trial and error and/or by observing the successes and failures of their peers. Educators can assess how deeply students are thinking as they are playing by observing students and whether they ask for clades of differing levels of inclusivity. Asking for more exclusive clades (e.g., dinosaurs aka Terrible Lizards) is generally riskier but it is also the initial novice asking tactic. Asking for very inclusive clades (e.g., reptiles aka Holey Heads) indicates a more thoughtful strategy as it is a better asking tactic when a player knows little about their opponent’s hand or the student is collecting several crown clades within Holey Heads. Asking for specific animals is very risky but players who do so successfully are likely listening closely to the asks of their opponents and are using this information to deduce the identities of the cards they hold.

Educators can ask players why they decided to ask in a certain way and students who are thinking critically will be able to explain their answer using the cards they have in their hand, the size of the clades they are trying to collect, and how much information they have gleaned from listening to other players. (It may be best to get their answer in writing so that they do not have to give away strategic information to answer you!) Encourage your students to discuss their strategies with each other after the game has ended. Like all good games, there is no one “right” strategy in Go Extinct!

In addition to the game itself, the post-game worksheet is designed to help students transfer their skills from the game onto more traditional-looking evolutionary trees. Students work together in game groups and this presents an opportunity for students to teach and learn from one another in a structured format. The questions increase in difficulty with the final question stumping most students and providing an opportunity for educators to engage students in conversations that touch on more advanced tree-thinking concepts. Encourage groups of students to work together on the post-game worksheet and to reference the pre-game worksheet for ideas on how to address the last question of the post-game worksheet. Students who review the pre-activity worksheet get to self-assess their earlier work and, in many cases, they see how much they have mastered in less than an hour’s worth of practice.

Modifications

Gameplay takes up most of the lesson, and some student groups may not finish, especially for games of six players. If needed, you can shorten the game by about 15 minutes by removing half of the cards, i.e., one of each animal from the deck. I do not recommend this unless it is necessary because it will reduce some of the competition driving the strategy that ultimately fulfills the learning objective. However, a halved game will still work, and students will still benefit from practicing with the tree.

This lesson can be extended for longer class blocks (e.g., 75 minutes) in two ways. First, I have provided a second post-game worksheet (Supporting File S11) with answers (Supporting File S12) centered on the natural history reflected in the game. Instructors can hand this worksheet out to groups who have finished with the post-game worksheet (Supporting File S8) and encourage the group to tackle this new worksheet together. The natural history worksheet is designed to start conversations around monophyly, the evidence used to build trees, convergent evolution, and evidence of common ancestry. Instructors are encouraged to check in with groups and bring up talking points from Table 1 that are relevant to the group’s conversation. I estimate that this worksheet will take students about 15–20 minutes to finish.

Second, the lesson can be extended by engaging students in designing their own Go Extinct!-style game around the flora and fauna that interest them through the DIY Go Extinct! online tool. This is a free resource where students pick a phylogeny and customize it by choosing animals to represent each clade as well as a wealth of aesthetics options. The trees available are centered around Australian flora and fauna, representing clades such as animals (Great Barrier Reef), dinosaurs, marsupials, venomous snakes, megafauna, and flowering plants. As students customize their game, instructors can ask them to identify what types of evidence are used to identify clades, the scientific rationale for the clade nicknames, and whether the entire board they are creating represents a very inclusive or exclusive monophyletic clade. At the end, students can print the materials for their game including cards and boards that reflect their customizations. This activity takes about 20–30 minutes.

Supporting Materials

• S1. Go Extinct – Cards

• S2. Go Extinct – Tiled board

• S3. Go Extinct – Full board

• S4. Go Extinct – Rules

• S5. Go Extinct – Lesson slides

• S6. Go Extinct – Pre worksheet

• S7. Go Extinct – Pre worksheet answers

• S8. Go Extinct – Post worksheet

• S9. Go Extinct – Post worksheet answers

• S10. Go Extinct – NGSS alignment

• S11. Go Extinct – Natural history worksheet

• S12. Go Extinct – Natural history worksheet answers

Acknowledgments

Enormous thanks to the students from Stanford’s Introduction to Human Biology for inspiring Go Extinct!’s design. Many thanks to the Hadly and Weisbecker Labs, as well as the scientists at the Society for Vertebrate Paleontology conferences for play-testing early versions of the game. Thanks also to the teachers and students at KIPP SF Bay Academy and SF Brightworks for play-testing the game in middle and secondary school settings. I am grateful to Vanessa Kerr, Charlie Chung and the 328 Kickstarter backers who made it possible to publish the game with high quality illustrations by Anita Tung. Thanks to the students at the University of Queensland and the Queensland University of Technology for playtesting the game and lesson worksheets. Many thanks to Taormina Lepore for running this lesson with her students and providing valuable feedback. I am very grateful to Michelle Smith and Erin Vinson for hosting the 2020 CourseSource Writing Studio, which jump-started this lesson plan into existence. During the Writing Studio, Paige Littman, Bernadette Connors, Samantha Ganser, and Deidre Jaeger provided helpful feedback on an early draft of the manuscript.

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