Despite the numerous advantages of using inquiry, many teachers do not use this method because of issues such as time constraints and increased workload. In addition, content such as evolution is particularly problematic to teach because of the perceived lack of hands-on activities and societal pressures. This inquiry activity is designed to help students understand an important component of evolution by natural selection. Through this activity students better understand natural variation within populations using peanuts. Students are encouraged to make links between population data, population diversity and evolution by using collected data to construct and interpret graphs. This article promotes National Science Education Content Standards A, C, and G, Iowa Teaching Standards 1, 2, 3, 4, and 5

Evans, Christine

Kasuga, Lindsay M. C.

University of Northern Iowa

Iowa Science Teachers Journal Volume 36 Number 3 Article 4 2009 Nuts about Inquiry: Peanut Variation and Natural Selection Lindsay M. C. Kasuga Christine Evans Follow this and additional works at: https://scholarworks.uni.edu/istj  Part of the Science and Mathematics Education Commons Let us know how access to this document benefits you Copyright © Copyright 2009 by the Iowa Academy of Science Recommended Citation Kasuga, Lindsay M. C. and Evans, Christine (2009) "Nuts about Inquiry: Peanut Variation and Natural Selection," Iowa Science Teachers Journal: Vol. 36 : No. 3 , Article 4. Available at: https://scholarworks.uni.edu/istj/vol36/iss3/4 This Article is brought to you for free and open access by the Iowa Academy of Science at UNI ScholarWorks. It has been accepted for inclusion in Iowa Science Teachers Journal by an authorized editor of UNI ScholarWorks. For more information, please contact scholarworks@uni.edu. ABSTRACT: Despite the numerous advantages of using inquiry, many teachers do not use this method because of issues such as time constraints and increased workload.  In addition, content such as evolution is particularly problematic to teach because of the perceived lack of hands-on activities and societal pressures.  This inquiry activity is designed to help students understand an important component of evolution by natural selection.  Through this activity students better understand natural variation within populations using peanuts.  Students are encouraged to make links between population data, population diversity and evolution by using collected data to construct and interpret graphs. This article promotes National Science Education Content Standards A, C, and G, Iowa Teaching Standards 1,2,3,4, and 5.Evolution is a challenging topic.  Many science teachers struggle to teach it, and many students struggle to understand it.  This s which aim to prostruggle is, in part, due to theHands-on does not guarantee minds-on.  Teachers must use caution when choosing activitie mote  political controversy associated student understanding.  Many “hands-on” activities fail to with teaching the topic. The problem is exacerbated by a lack of mentally engage students; rather, these activities tell hands-on activities that promote deep student learning.  students what and how to think.  The danger of these Understanding evolution is particularly challenging because of activities, termed “cookbook” activities, is that they often the numerous smaller concepts, such as natural selection, hinder students' development of a deep and robust variation within populations, selective pressures, differential understanding of  fundamental  science ideas.  survival, genetics, and reproduction that interact to support the Unfortunately, the manipulation of objects masks the lack of main idea of evolution.  The challenge for teachers is to select mental effort.  and present materials and activities that scaffold students from these smaller concepts to how these components fit together to In contrast, inquiry based activities promote student form a cohesive picture of evolution. understanding by requiring mental activation and Lindsay M. C. Kasuga and Christine Evansusing Peanut variation to teach natural selectionNuts aboutInquiry08Iowa Science Teachers Journalhttp://ists.pls.uni.edu/ISTJVolume 36, Issue 3, Fall 2009Copyright 2009 Iowa Academy of SciencePhoto by Manoel Silva  Graphics Work by Joe Taylorengagement.  When used effectively, inquiry activities Once students have reviewed previous content, we promote many of the goals we have for our students introduce the task for the day by saying, “Since some including deep and robust understanding, teamwork, variations are selected for more frequently then others, we effective communication, problem solving and critical are going to spend some time investigating variations in thinking.  Yet, planning inquiry activities can be organisms.” We challenge students by askingoverwhelming.  Instead of starting from scratch, we have modified a “cookbook” lab so that it requires students to be  “What characteristics of a peanut could we use to more meaningfully and mentally engaged. measure variation within a population?” At this point students usually say mass or length; this can lead to a fruitful discussion regarding what characteristic In the original activity, students are given a paper lab and are would be best for measuring.  During this discussion we ask instructed to begin the task with little instruction and no rationale follow-up questions such asfor doing the activity.  Students crack open and measure the length of thirty peanuts and then record their results on the “What are the pros and cons of using mass to measure provided graph.  While this activity seeks to demonstrate the variation within a population?" important concept of natural variation within populations,  "What are the pros and cons of using length to students do not develop a deep and robust understanding of this measure variation within a population?"  concept because little cognitive effort is required to complete the "What additional considerations, such as limitations of task.  Students are told how to measure, how to plot their data, the classroom, do we need to consider when choosing and there is no explicit connection made to previous activities or what characteristic to measure?” material covered in class.  However, all was not lost!  We realized how we could modify this activity to help our students By helping students determine what characteristic to make meaningful connections to big ideas and promote critical measure, they develop a better sense of ownership and and creative thinking in our students.  engagement in the activity because their ideas help steer the direction of their investigation. Before beginning this acIn order for our discussions to be fruitful, we are careful not to respond to student ideas too quickly.  Rather, we wait for other students to comment.  We want students to evaluate uracy of student's each other's ideas and make decisions, not wait for us to statements.  If there is a peanut allergy, an alternative item simply tell them what to do.  In addition to waiting, we move will have to be used; suggestions include beans or any type and look arouof naturally variable produce.  The key point here is that the trait being measured, such as length or width, is variable within the population.  If using an object besides peanuts, the teacher should perform the lab before students to ensure s.  If students do not variability within the population.share their ideas, we cannot know what they are thinking.One of the most important modifications we made was Before distributing the items to be measured, we ask connecting the lab to previous classroom discussions and students to come up with a procedure for investigating the activities.  By asking a few review questions regarding the variation in the peanuts.  We guide the discussion by asking process of natural selection, we help students develop a questions such as context for the investigation.  In previous class sessions, students had been introduced to the idea of natural selection “What unit should we use to measure the peanuts?”and this investigation adds to the idea by incorporating “How are you going to record your results?"  natural variation and differing selective pressures into the "What are the pros and cons of using this particular process of evolution. To help students make connections to method to record results?”previous learning, we ask them to review with their partners what they know about natural selection.  While they discuss, So that they think more deeply about their decisions, we we walk around the room and pose follow-up questions and expect students to defend their approach.  Notice, we are listen to see what conceptual hurdles students have yet to not simply giving the students directions, but we are leap.  Some questions we ask includeproviding carefully thought out guidance so that they are successful.  While this approach may take more time, the “What might cause a mutation to be selected for by demand placed on student thinking is worth it.nature?”“How might the selection process result in changes to Sometimes we have students collect their length data before the population?”discussing how to analyze the data; sometimes we discuss The Original ActivityInvestigating Peanutstivity, poll your students to determine if there are any peanut allergies.  In addition to talking to students, you might also talk with the school nurse or other health official to ensure the accnd the room expecting students to comment.  We do not evaluate or critique student ideas at this point, but instead ask for clarification or seek other ideas.  We use this approach in order to maintain open dialogue in which students feel safe sharing their idea• • • • • • • • • Volume 36, Issue 3, Fall 2009Copyright 2009 Iowa Academy of Science                  Iowa Science Teachers Journal                           http://ists.pls.uni.edu/ISTJ09 analyzing the data first.  In either case, we ask students how they might “visualize” their data.  Students usually quickly The next important step in this investigation is to connect say we should graph the data, but then we ask what kind of students' observations to the larger processes of evolution.  graph we should make. Students often struggle with this To help students understand how this natural size variation question largely because they are not accustomed to having is a critical component in the process of evolution, we pose a to make such decisions.  scenario to students. Many students will want to initially create a line (x,y scatter “Imagine a predator enters the peanut field and because of plot) relating peanut number (determined randomly as a by- its small beak is able to eat only peanuts smaller than fifteen product of data recording) and peanut length.  At this point, millimeters.  How do you predict this would change the size we intervened by asking students distribution of the peanuts?”  “What data are typically plotted using line graphs?” Some students struggle with this question and we have to  "What might a line graph convey about the data?"  ask other questions to help students understand the  "What sort of information are we trying to convey scenario.  We use questions such as regarding our data collection?”  “Think about the fact that genes are passed from By asking these questions, students can be guided to realize parents to offspring.  What would happen if only that these data are not appropriate for a line graph.  We then peanuts smaller then fifteen millimeters are eaten?” asked another question Students will typically say that there will be fewer small  “What other graphs have you used to help represent data?” peanuts in the next generation.  Students will often say bar graph and pie charts. Using a At this point, we empty any tubes with small peanuts to help questioning pattern similar to that outlined above, we guide students concretely track their thinking.  We then askstudents to the idea that a bar graph would most appropriately represent their data because we are  “How might having fewer small peanuts in the field interested in the number of peanuts in a given length range. impact the number of larger peanuts in the next To help students understand how graphs abstractly generation?” We help students understand that there will be a corresponding increase in the number of large peanuts.  Then, students add more peanuts to the appropriate size tube to represent the increase in number of larger peanuts in the next generation (Figure 3).  Once again, students are asked to observe the tubes and, more importantly, to note similarities a n d  d i f f e r e n c e s  between the size represent data, we created a series of tubes designed to distributions.  hold the peanuts grouped by length (Figure 1).  Students then place their peanuts in the appropriate tube.  Once all By being asked to think the peanuts are placed into the tubes, students discuss what through the scenario they observe about the tubes.  Students often first notice and being supported in that there are more of the middle-sized peanuts and fewer the i r  th ink ing  by  peanuts of the largest and smallest sizes (Figure 2).  physically manipula-Students, provided with the concrete experience of creating ting the number of this size distribution, more easily understand an abstract peanuts in the tube, representation of the tubes using graph paper. students come to realize that the size distribution will shift to larger size peanuts.  Once students have d e v e l o p e d  t h e i r  understanding of the concept, we then introduce the term directional selection.• • • • • • Bridging Data and TheoryTUBE MATERIAL LISTBase: 2x4 boardsVertical supports: 5/8-In dowelsTubing:  1-3/4 inch diameter clear tubingZip tiesCONSTRUCTION TIPFor a more economical and quick way to create the “peanut graph” we have found small diameter graduated cylinders to be useful.FIGURE 1One tube unit of the concrete representation of a bar graph.10Iowa Science Teachers Journalhttp://ists.pls.uni.edu/ISTJVolume 36, Issue 3, Fall 2009Copyright 2009 Iowa Academy of SciencePhoto by Lindsay Kasugaaccurately predict how these predators, described above, Using a procedure similar to that outlined above, we pose would change the shape of the distribution curve; we label two additional scenarios: these situations as disruptive selection and stabilizing selection, respectively.  “Imagine a predator enters the peanut field and because of the shape of its beak is able to eat only peanuts between the sizes of fifteen and twenty-five millimeters.  How do you predict this would change the size distribution of the Our guiding questions throughout this activity highlight the peanuts?” and critical role of the teacher in inquiry activities.  In traditional cookbook activities the students can often perform the task “Imagine a predator enters the peanut field and because of without the teacher even being present!  In contrast, inquiry the shape of its beak is able to eat only peanuts smaller than activities demand much more of teachers.  Instead of simply fifteen millimeters or larger than twenty-five millimeters.  telling students answers we encourage them to reason How do you predict this would change the size distribution of through and use their previous learning to make sense of the peanuts?” information.  Ofards for both the teacher and students are well worth the effort.    Clough, M. P., & R. Clark (1994).  Cookbooks and Constructivism: A Better Approach to Laboratory Activities.  The Science Teacher, 61(2),  34-37.Rowe, M.B.  (1986).  Wait-time: Slowing down may be a way of speeding up.  Journal of Teacher Education, 37(1), 43-50.Students, after given time to think-pair-share and manipulate the number of peanuts in the tubes, can usually ConclusionReferencestentimes the most important thing we can do to encourage students to think is to reduce the amount of our own talking.  Although teaching through inquiry is demanding, the rewQUICK TIPDepending on your purpose, consider dying or marking in some way the “next generation” peanuts so that students can more easily distinguish between the P and F1 generations.FIGURE 2Students add peanuts to the tubes and notice a distributionsimilar to this photo.FIGURE 3Students add peanuts to subsequent generations and observe how the populations pattern changes.Lindsay M. C. Kasuga teaches in the Douglas County School District in Castle Rock, Colorado.  Her areas of emphases include biology, chemistry, and aquatic biology.  Lindsay can be reached at lmckasuga@gmail.com. Christine Evans is a teacher in Chicago, Illinois.  Her teaching areas include biology, chemistry, and general science.  Christine can be reached at cjurinek@gmail.com.Volume 36, Issue 3, Fall 2009Copyright 2009 Iowa Academy of Science                  Iowa Science Teachers Journal                           http://ists.pls.uni.edu/ISTJ11Photos by Lindsay Kasuga

Nuts about Inquiry: Peanut Variation and Natural Selection

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Nuts about Inquiry: Peanut Variation and Natural Selection

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