The Scientific Method: The World As Your Lab—Chemistry

Out of the Cookbook into the Kitchen

Science is the process of learning how the world works. Students come to class to learn about the world, but the world in the classroom often does not correspond to the world where they live their lives. Bridging the divide between these two worlds can be difficult and requires that students apply the same skills and thinking from the classroom to where they live.

Minerva’s mission to provide our students with practical and transferable knowledge is enabled by a dedicated effort to ensure students have opportunities to apply the concepts they are learning in the classroom to the world around them and to themselves. This is especially important in the Natural Sciences in which theoretical knowledge should be paired with hands-on experimentation and observation so that students can explore the full scope of the scientific method. At many traditional institutions, this is typically facilitated through laboratory courses. While these lab courses have the potential to offer valuable learning experiences, they tend to emphasize procedural information and skills, rather than engaging students in inquiry-based hypothesis development, experimental design, and analysis. At Minerva, rather than simulate real-world phenomena in a lab, students make a lab out of the real world.

Every course at Minerva has a “location-based” assignment, meaning that it includes certain elements that require students to go out and interact with their city of residence. This series will showcase examples of such assignments across different disciplines within the Natural Sciences, including physics, chemistry, and environmental sciences.

The assignments presented in this series can serve as examples to inspire educators to incorporate experiential learning in their Natural Science courses. All examples share a few common elements:

• An emphasis on real-world, hands-on, project-based learning. Students should have opportunities to make connections between the course content and the world around them.
• An emphasis on defining the learning outcomes. Assignments at Minerva are always designed around granular learning outcomes that relate directly to the learning outcomes of the course.
• An emphasis on the analysis. Getting the “right answers” isn’t the goal of these assignments. Instead, the focus is on the “right explanations.” Students are prompted to justify their approaches and interpret their results in full.
• Adaptability. Even though these are “location-based” assignments, they are not tied to a particular location — they can be done from anywhere! Further, depending on what is asked of students in the analysis, these assignments can be delivered at various levels of complexity and sophistication, from introductory courses to senior concentration classes.
  
  

The Assignment

“Cookbook labs” are common accompaniments to undergraduate courses in the sciences, but they are not the best recipe for success in a career in science. In a “cookbook lab” session, students follow an established protocol to obtain an expected result. While this is certainly a useful experience, these lab sessions have limitations. They are often expensive, requiring access to specialized equipment and reagents, and they do not typically engage students deeply in key components of scientific inquiry: observation, hypothesis development, optimization of methodology, etc. Additional translational skills, like problem-solving, working within constraints, troubleshooting, and communication, are not always practiced in traditional lab exercises.

Our solution is to take the lab out of the cookbook, quite literally! In our junior-level Life’s Chemistry course, our students design a research project that can be completed safely in the kitchen, to investigate a research question related to the process of fermentation.

EXPERIMENTAL METHODS USING COMMON KITCHEN EQUIPMENT

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A — Maya Cohen measured the relative CO2 production of sourdough cultures using balloons to trap the gas and an inexpensive pH meter to track changes in acidity.

B — Trang Nguyen used balloons to measure the relative CO2 production of black rice fermentation.

C — Nazar Yaremko measured the growth of kombucha SCOBY (symbiotic culture of bacteria and yeast) by weighing the SCOBY on a kitchen scale and measuring the depth of SCOBY in glass jars.

D — Blerim Jashari measured the relative viscosity of yogurt cultures by dropping measured amounts of yogurt onto a plastic-wrap-covered inclined plane. The student used a cell phone stopwatch and a ruler to measure the distance traveled in a specified time. Then, the student used an inexpensive pH meter to measure the acidity of the cultures.

The lab experience for Life’s Chemistry is completed throughout the semester in three phases that help students to engage with the complete process of the scientific method. These three phases are:

• Question and reflection
• Process, not perfection
• Results and presentation

Phase 1: Question and reflection:

An essential skill to master as a scientist is asking the right questions. Scientists must build on what others have observed or documented and consider the scope and feasibility of a project to find a fruitful question for research.

With a bit of observation and a dash of creativity, interesting research questions can be found everywhere. For the Life’s Chemistry project, students begin by exploring the cuisine of their local culture, seeking out a fermented food or beverage for investigation (students must select a product that results in less than 2% alcohol by volume, which means they can select a product like kombucha, but not beer or wine). The students research the fermentation process for this product, using a variety of resources including recipes, blogs, local producers or experts, and, of course, peer-reviewed primary papers. They begin to frame a question as they draft a literature review. The literature review requires students to connect concepts from class; for example, by analyzing the thermodynamics of a key reaction in the fermentation and by explaining how an enzyme facilitates the catalysis of the reaction.

While beginning the literature review, students simultaneously set up their first attempts at producing the fermented food or beverage. They use a lab notebook template to take careful notes of their process and observations.

At the end of this phase, students combine what they have learned from their own observations and their review of the literature to frame a research question and testable hypothesis. Many students asked straightforward questions, such as “how does incubation temperature influence the rate of fermentation (measured by the change in pH) in yogurt?” Others asked more complex questions that do not have clear answers in the literature, such as “how does iodized salt influence the fermentation rate of sauerkraut”?

Phase 2: Process, not Perfection

Scientists must be able to determine what methods are best suited to answering their questions. This is an area in which common “cookbook labs” fall short, as the methods are given to students as instructions to follow. Scientists must learn not only how to follow a protocol, but how to design and test one.

In the Life’s Chemistry project, students design their own experiments to test their hypotheses. They must work with the constraints of time, budget, and space in their kitchen to design feasible experiments that can be conducted with rigor. Students learn to keep detailed lab notebooks, noting protocols, observations, and results. This is an iterative process, and many students realize shortcomings in their initial methodology that they improve in the next round.

In this project, there is no “right” answer; students must determine how to assess their own methods to determine if the data collected is of sufficient quality to answer the question. Most students finished the semester with a long list of strategies to improve their methods should they conduct the experiment again. Students examined the shortcomings and failures to evaluate where they went wrong and how to improve. We believe that these “right explanations” are more valuable to student learning than simply getting the “right answer”.

Phase 3: Results and presentation

Scientists must communicate the results of their experiments with a variety of audiences, including peers and the general public. To practice this communication, students in Life’s Chemistry synthesize their semester-long project into a formal research paper and a short oral presentation. The paper is completed iteratively and following a standard format, building on the initial literature review and incorporating methods and results as they are collected. Students have the opportunity to get feedback and revise this heavily-weighted final project.

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EXAMPLE EXPERIMENTAL DESIGN AND RESULTS BY ALICIA, CLASS OF 2022

A — Alicia hypothesized that if two different strains of probiotic bacteria (S. thermophilus and L. Bulgaricus) were used to culture yogurt, more lactic acid would be produced in the mixed culture than in pure cultures, resulting in a lower pH.

B — A visual representation of Alicia’s experimental design. Alicia used six replicates for all conditions and measured pH with a pH meter.

C — Timecourse of changes in pH in each culture. You can observe that the yogurt ferments, producing lactic acid and lowering the pH of the cultures. No change in pH is seen in the control condition, which does not contain cultures of bacteria.

D — Comparison of the change in pH at 12 hours shows a small difference in the change in pH in the mixed culture compared to either pure culture. All cultures have a significantly greater change in pH than the control group. Alicia interpreted that these results supported the hypothesis, but that additional replicates should be completed, and Alicia proposed a number of interesting follow-up questions for further research.

Tips for Creating Your Own Location-Based Lab

Whether you and your students have access to a state-of-the-art lab or are getting creative in the kitchen, there are many ways that you can incorporate elements of this process into your laboratory course.

Phase 1: Question and reflection

• Ask students to observe a phenomenon related to your experiment.
• Have students conduct a brief literature review or a simple annotated bibliography to explore the literature on the method.
• Have students brainstorm questions that could be explored with the method they are learning.
  

Phase 2: Process, not perfection

• Ask students to design their own experimental methods to solve a very simple problem. It is very useful to go through the practice of determining how to complete an experiment precisely and objectively.
• Give students several slightly different protocols to complete the same assay. Ask students to evaluate the differences in methods.
• Adapt a “cookbook” lab to contain some missing or deliberately suboptimal steps that students must problem-solve or troubleshoot to find the best solution.
• Ask students to write reflections on why a protocol works (or why one fails!)
  

Phase 3: Results and presentation

• In addition to turning in the lab report, ask students to share results in multimedia formats such as “chalk talk” presentations, blogs, videos, webpages.

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