Activity pubs.acs.org/jchemeduc
Activities for Middle School Students To Sleuth a Chemistry “Whodunit” and Investigate the Scientific Method Audrey F. Meyer,#,† Cassandra M. Knutson,#,‡ Solaire A. Finkenstaedt-Quinn,† Sarah M. Gruba,† Ben M. Meyer,† John W. Thompson,† Melissa A. Maurer-Jones,† Sharon Halderman,† Ayesha S. Tillman,§ Lizanne DeStefano,§ and Christy L. Haynes*,† †
Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455 United States Science Department, White Bear Lake High School, White Bear Lake, Minnesota, 55110 United States § Department of Education, University of Illinois, Champaign, Illinois, 61820 United States ‡
S Supporting Information *
ABSTRACT: The recent increased public interest in forensic science, sparked in part by television shows such as CSI and Bones, presents an opportunity for science educators to engage students in forensic chemistry-themed activities to introduce fundamental concepts, such as the scientific method. In an outreach setting, mysteries were used as a way to engage middle school students to select forensics tests, form hypotheses, make observations while conducting the tests, consider positive and negative controls, and use the results to reach conclusions. Student data shows that the outreach activities generally increase student understanding of the scientific method. These activities have been translated from outreach activities into accessible activities for middle and high school classrooms.
KEYWORDS: Elementary/Middle School Science, Analytical Chemistry, Laboratory Instruction, Problem Solving/Decision Making, Forensic Chemistry, High School/Introductory Chemistry, Public Understanding/Outreach
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n recent years, public interest in forensic science has increased greatly in part because of television shows such as CSI and Bones, which feature scientists using analytical tools to solve crimes.1,2 Although these shows contain many scientific and legal inaccuracies,1 the increased public interest in forensic science presents an opportunity for chemists to engage students in the science behind chemical tests featured on television.2 By leveraging student interest in the applied nature of forensic chemistry, educators also have an opportunity to use a practical, problem-solving approach to introduce students to the scientific method,3 including formulating hypotheses, selecting an appropriate experiment from those available, performing positive and negative controls, and interpreting both conclusive and inconclusive results. In this outreach activity, middle school students (ages 10− 14) in a summer program at a community center were invited to participate in a forensic science mystery-solving activity (Figure 1). The students were asked to select an assay, consider positive and negative controls, and use information gained from several assays to reach a conclusion and solve a mystery. Three mysteries were presented in consecutive years to students attending a summer program at the West Seventh Community Center in St. Paul, Minnesota. Mysteries included an environmental chemical spill, a jewel heist, and a case of sabotage at a solar cell factory. In the first and second years, students watched a video wherein an investigator described the © 2014 American Chemical Society and Division of Chemical Education, Inc.
Figure 1. Students in a summer program participating in a forensic science mystery-solving activity.
mystery and interviewed a cadre of suspects. Students also viewed a short video describing the assays available to them. Working in groups of four, students were given a kit of evidence and challenged to solve the mystery. In the third year, a similar format was followed for the sabotage with the exception that the students did not watch a video of the demonstrations of the assays available. In the second and third Published: January 27, 2014 410
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Table 1. Overview of the Evidence Kit Contents and Available Assays for the Three Mystery Activities activity Chemical Spill
Jewel Heist
Solar Cell Factory Sabotage
a
contents of evidence kita
assays available to students
contaminated river water sample handwritten notes found in contaminated area pens belonging to suspects map with fingerprints and fingerprint samples from suspects soil sample from contaminated area homogenated fish sample from contaminated area fingerprint samples from each suspect debris from crime scene with fingerprint present glass from the display case glass found in a suspect’s car powder found at crime scene powder samples found on suspects paint collected from security camera paint from a suspect’s hands paint sample from a mural (suspect’s alibi) piece of plastic left at crime scene pieces of plastic from the workplaces of suspects sample containing DNA from a cup at the crime scene DNA sequence preprocessed from each suspect handwritten note found at the crime scene pens belonging to suspects metallic dust found at the crime scene metallic dust found on shoes of suspects fingerprint samples from suspects piece of paper with fingerprint found at crime scene sample of scent detected at crime scene cologne or perfume from suspects
acid−base detection of metal ions in solution ink chromatography flame test iodine fingerprint developing or ninhydrin fingerprint developing luminol test pH test acid−base detection of metal ions in solution ink chromatography iodine fingerprint developing or ninhydrin fingerprint developing nanoparticle test for pesticides iodine test for starch
plastic density comparison DNA extraction metal ion flame test ink chromatography iodine fingerprint developing or ninhydrin fingerprint developing silver-plating test
Positive and negative control samples should be provided to students at the assay stations.
stations to explain the chemistry concepts of the assay, how to perform the assay, and positive and negative controls where applicable. For all three activities, evidence kit contents and assays available to the students are listed in Table 1. Detailed preparation instructions for the evidence kits, the assays, and positive and negative controls can be found in the Supporting Information. In scenario 1, Chemical Spill on the Mississippi River, students watched a video that explained that a portion of the Mississippi River was mysteriously lacking in fish and wildlife and watched investigator interviews with the suspects that might be causing this environmental change. In scenario 2, Jewel Heist at the Science Museum, students watched a video that explained that the crown jewels on display at the science museum had been stolen during a break-in, and they were shown interviews with suspects. In scenario 3, Sabotage at a Solar Cell Factory, students watched a video depicting a crime of sabotage at the Solar Haynes Industries solar cell factory, including police investigator interviews with potential suspects. Students were presented with four suspects and five or six assays with which to test their evidence for each scenario. It is possible to change the guilty suspect by altering the evidence apparently collected from each suspect. In addition to the use of several well-known tests widely used in outreach activities (DNA extraction, starch detection with iodine, filter paper chromatography with felt-tip pens), we incorporated a series of less well-known tests that demonstrate chemical reactions. Some of these include an acid−base detection of metal salts in scenario 1 and a nanoparticlebased test for pesticide detection.
years of the activity, students were asked multiple-choice preand postactivity questions about important scientific vocabulary. They used personal response devices, which have received generally positive student reviews,4,5 to answer the questions, and student answers were analyzed to evaluate student learning during the course of the activity. Results of the student answers to pre- and postexperiment questions are included: in year 2, student comprehension increased for two of the four questions asked from the preactivity assessment to the postactivity assessment, and in year 3, increases in student comprehension were observed for all four of the questions from the pre- to the postactivity assessment.
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ACTIVITY FORMAT This activity involves preparation beforehand of these elements: (i) a video (or other format presentation) detailing the events of the mystery to students, (ii) evidence kits, and (iii) solutions for assays. The format of the activity as well as the assays made available to students are described herein, and detailed transcripts of the three mystery videos as well as instructions for preparation of the evidence kits and assays can be found in the Supporting Information. Students watched a short video written, directed by, and starring University of Minnesota graduate and undergraduate students. Student participants were then split into groups of four and assigned to a graduate or undergraduate “guide,” who helped keep the students on task during the activity. Students were given a box containing approximately six pieces of evidence that they were told had been collected from the suspects or at the crime scene and a list of stations where they could test their evidence. Graduate or undergraduate students were available at each of the assay 411
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Table 2. Comparison of Correct Student Responses to Pre- and Postactivity Assessments Jewel Heist Activity, N = 24
Solar Cell Factory Sabotage Activity, N = 27
assessment questions
preactivity, %
postactivity, %
preactivty, %
postactivity, %
Question 1: What is an observation? Question 2: What is a hypothesis? Question 3: What is a positive control? Question 4: What is a negative control? overall percent correct
79 67 50 46 60
79 58 63 71 68
70 78 30 22 52
74 89 53 48 68
box containing samples of evidence matching the samples collected in the video, a set of worksheets to guide them, and access to between four and six stations where they could perform chemical assays on the evidence in the kit. Students were given no instructions regarding which assay to use on which piece of evidence. For each assay, students recorded the evidence tested and the results of the assay as well as the results of the positive and negative controls. Students were also asked to interpret their results in the context of the mystery. Once all students had completed the activity and made their conclusions about the potential suspects, they were asked Questions 1−4 again. During the Jewel Heist Mystery activity, all groups solved the mystery correctly, and the percentages of students answering the preactivity questions and postactivity questions correctly are listed in Table 2. Of the four questions asked, the percentage of students answering correctly increased from the pre- to the postactivity assessment for Questions 3 and 4 (by 13 and 25%, respectively), did not change for Question 1 (0.0% change), and decreased for Question 2 (−8.3%). The increase in overall student scores from 60% before the activity to 68% after the activity was found to be nonsignificant using a twotailed t-test (p = 0.5). On the basis of the results in Table 2, it was clear that increased emphasis on the concepts of the scientific method (observations, hypotheses, and controls) was needed to increase student comprehension of the scientific method during the activity. As the goal of this activity was for students to learn through problem solving rather than direct instruction, preparations for the assay stations for the following year (Solar Cell Factory Sabotage) focused on improving emphases on observations, hypotheses, and controls. In doing so, students were exposed to these principles through the miniexperiments that they performed at each assay station. During the Solar Cell Factory Sabotage Mystery activity in year 3, students were asked the same questions before and after the activity as for the Jewel Heist Mystery. Overall student scores increased significantly from 52 to 68% (p = 0.03). The percentage of students answering correctly increased from the pre- to the postactivity assessment for all four questions asked. The increase in students correctly answering was 3.7% for Question 1, 11% for Question 2, 22% for Question 3, and 26% for Question 4. To assess the statistical significance between pre- and postactivity responses, the student responses to each question for both of the activities were pooled. Using McNemar’s test,9 the pooled responses showed a significant increase in comprehension for Questions 3 (p = 0.01) and 4 (p = 0.01). Significant differences between the pre- and postactivity responses were not observed for Questions 1 (p = 0.6) and 2 (p = 0.6). These results indicate that an outreach activity with no direct instruction can lead to significant increases in student comprehension of concepts related to the scientific method and
All mystery scenarios were tested with students ages 10−14 in a one-day event for socioeconomically disadvantaged students (an average of 74% of students identify as racial minorities, and 87% of students were from homes below 200% of the federal poverty guidelines) participating in a summer program.8 Although the mysteries were developed for use in an outreach event, all activities were translated and optimized by a certified Minnesota high school teacher for use in middle and high school classrooms because some tools and materials may be inaccessible to middle school classrooms. Changes made to the tests for middle school classrooms include preparing nanoparticles in advance for the silver nanoparticle aggregation test used in scenario 2 according to a previously published protocol6 and inducing aggregation by the addition of a salt.7 Also for scenario 2, paint samples were composed of mixtures of washable paint, and in postactivity optimization, it was determined that black tempera paint and black acrylic paint (readily available and inexpensive at craft stores) would be easier for implementation in a classroom. In scenario 3, a DNA isolation procedure was used that required the use of a centrifuge; however, because many middle and high school science classrooms may not have a centrifuge, an additional DNA isolation procedure is included in the Supporting Information. A library of detailed descriptions of each scenario as well as teacher guides for implementation in a middle school classroom can be found in the Supporting Information.
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HAZARDS AND SAFETY CONSIDERATIONS Safety hazard information and proper waste disposal procedures for the supplies used in each activity can be found in the Supporting Information. Gloves and goggles should be worn for all activities. Caution should be exercised when using an open flame. Iodine, silver nitrate, and ninhydrin can stain clothes and skin.
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RESULTS AND DISCUSSION Three different mysteries were developed and implemented in three consecutive years, and student learning over the course of the activity was evaluated in the latter two years. Some students participated in the summer program for multiple years, leading to a small degree of overlap between students each year. Students were asked several multiple-choice questions both before and after solving the mystery: 1. What is an observation? 2. What is a hypothesis? 3. What is a positive control? 4. What is a negative control? They then watched a video in which an investigator described the mystery scenario, interviewed suspects, and collected evidence, followed by a short video with instructions for the assays available to them. Students were then divided into groups, in which each group had a guide and was given a 412
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Author Contributions
are promising for student learning when implemented in a middle school classroom. Although the focus of the investigations when implemented as an outreach activity was on engaging students in solving a mystery through problem solving using chemical assays, each investigation contains multiple activities that could be used to highlight a number of different chemical concepts, including solubility, acid−base chemistry, chemiluminescence, and atomic emission spectroscopy. Using a format with minimal direct instruction and instead allowing students to determine which chemical tests were appropriate for certain types of samples, student comprehension of concepts related to the scientific method increased when these concepts were emphasized during the explanation of the assay protocols. Results from the implementation of this activity at a community center were used to optimize the activities for use in middle and high school science classrooms, including details regarding how these activities meet national science standards. The optimized versions of the activities are presented here, with input and perspectives from two high school teachers as to the choice of materials used and the questions presented on student worksheets during the activity. The Supporting Information contains activities as three separate and complete investigations, including a teacher guide, student handouts, and assay protocols, with each considering learning objectives such as making observations, organizing data, and drawing conclusions from data.
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These authors contributed equally.
Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS This work was funded by a grant from the National Science Foundation to the Center for Sustainable Nanotechnology, CHE-1240151. The authors would like to acknowledge Daniel Bakke, Kyle C. Bantz, Srishi Batra, Anushua Bhattacharya, Joseph Buchman, Antonio Campos, Cole Christianson, Ashish Datt, Samuel M. Egger, Zhe Gao, Clifford Gee, Ian L. Gunsolus, Mehrdad Hairani, Rachel N. Hanson, Chris Huber, Katherine R. Hurley, Kadir Hussein, Jolene L. Johnson, Brynna Jones, Donghyuk Kim, Nathan Klein, Secil Koseoglu, Leah Laux, Yu-Shen Lin, Sara A. Love, Drew Maurine, Benjamin M. Manning, Aaron M. Massari, Sara J. Olson, Heidi Nelson, Alec Nicol, Gabriella Perell, William C. Pomerantz, Tian A. Qiu, Hattie L. Ring, Zahra Sohrabpour, Matthew Styles, Victoria Szlag, Andrew Urick, Yiwen Wang, Xiaojie Wu, and Ashlyn Young for participating in these activities each year. We thank the staff and students at the West Seventh Community Center in St. Paul, Minnesota for welcoming the activities into their summer program and Joseph Franek for providing demonstration materials. In particular, the authors would like to acknowledge William C. Pomerantz, Clifford Gee, Drew Maurine, and Andrew Urick for their work on development and implementation of the DNA and ninhydrin fingerprinting tests. This work was supported the NNIN Research Experience for Teachers awards to C.M.K. and S.M., and a UMN Doctoral Dissertation Fellowship awarded to A.F.M.
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CLASSROOM SCIENCE STANDARDS This activity includes components that address high school Next Generation Science Standards, including Practice 1, Asking Questions and Defining Problems; Practice 3, Planning and Carrying Out Investigations; Practice 4, Analyzing and Interpreting Data; Practice 6, Constructing Explanations and Designing Solutions; and Practice 7, Engaging in Argument from Evidence.10,11
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(1) Schweitzer, N. J.; Saks, M. J. The CSI Effect: Popular Fiction about Forensic Science Affects the Public’s Expectations about Real Forensic Science. Jurimetrics 2007, 47, 357−364. (2) Milanick, M. A.; Prewitt, R. L. Fact or Fiction? General Chemistry Helps Students Determine the Legitimacy of Television Program Situations. J. Chem. Educ. 2013, 90, 904−906. (3) Kazilek, C. J.; Pearson, D. Using the Scientific Method To Solve Mysteries. http://askabiologist.asu.edu/teaching-scientific-method (accessed Jan 2014). (4) Caldwell, J. E. Clickers in the Large Classroom: Current Research and Best Practice Tips. CBE Life Sci. Educ. 2007, 6, 9−20. (5) MacArthur, J. R.; Jones, L. L. A Review of Literature Reports of Clickers Available to College Chemistry Classrooms. Chem. Educ. Res. Pract. 2008, 9, 187−195. (6) Maurer-Jones, M. A.; Love, S. A.; Meierhofer, S.; Marquis, B. J.; Liu, Z.; Haynes, C. L. Toxicity of Brine Shrimp: An Introduction to Nanotoxicity and Interdisciplinary Science. J. Chem. Educ. 2013, 90, 475−478. (7) McFarland, A. D.; Haynes, C. L.; Mirkin, C. A.; Van Duyne, R. P.; Godwin, H. A. Color My Nanoworld. J. Chem. Educ. 2004, 81, 544A− 544B. (8) Murphy, J. Personal Communications to C. L. Haynes, 2011− 2013. Demographics of W. 7th Community Center. (9) Agresti, A.; Franklin, C. Statistics: The Art and Science of Learning from Data, 3rd ed.; Pearson: USA, 2012; p 504. (10) Quinn, H.; Schweingruber, H.; Keller, T. A Framework for K−12 Science Education: Practices, Cross Cutting Concepts, and Core Ideas; The National Academies Press: Washington, DC, 2012. (11) Next Generation Science Standards, Appendix F; Achieve, Inc. on behalf of the 26 states and partners that collaborated on the NGSS, 2013.
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CONCLUSION In the activity presented here, three separate investigations were developed in which students use simple chemical assays to solve a mystery. In each investigation, students were given a kit of evidence, a list of assays, and minimal direct instruction. Although this activity was originally designed as an outreach event, the activities were modified and formatted for implementation in a middle school classroom. Students work in groups, make decisions related to a course of action for solving a problem, formulate hypotheses, perform positive and negative controls, interpret data, and formulate conclusions based on results of multiple chemical assays. Instructors could also modify activities as needed for a greater focus on scientific concepts of interest to the class.
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ASSOCIATED CONTENT
S Supporting Information *
Student and teacher materials for the activities; descriptions of evidence kit preparation and assays used; teaching objectives for the activities. This material is available via the Internet at http://pubs.acs.org.
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REFERENCES
AUTHOR INFORMATION
Corresponding Author
*C. L. Haynes. E-mail:
[email protected]. 413
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