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Counting the Crumbs: Experimental Design and the Chemistry of Cookies

Teaching the scientific method through a baking project.

This lesson will help students:

  • Understand modern science as an inquiry-based approach advanced by carefully designed experiments.
  • Become familiar with the scientific method and how to apply this method in the real world.
  • Analyze collected data and present findings to peers.

Overall Objective

Too often students learn the scientific process as bystanders, never sitting in the driver’s seat to see the path that lies ahead on the journey to exploration of their natural world. Many students can rattle off the steps of the process with accuracy and precision, yet lack the capabilities to design a test of their own questions in the real world. Worse, students who cannot memorize the “facts” in science classes early on deem themselves “non-scientists” at an early age, forever deterred from understanding the beauty and wonder of the world around them.

This project, designed as an introductory project for chemistry students, strives to place students in the driver seat of inquiry while building the translatable skills of scientific communication and how to make correct measurements. In “The Great Cookie Project,” students begin by reflecting on their favorite chocolate chip cookies using descriptions that are both qualitative (sweet, soft, crunchy, brown) and quantitative (large, warm, ratio of chocolate chip to dough). 

After this reflection, they are asked to collaboratively design an experiment that answers one question about one aspect of a chocolate chip cookie. Going through the design process, students first research the variable they are examining: how does the ingredient or parameter they wish to change affect the cookie? How do the ingredients (or chemicals) react with each other to make a cookie? They discuss what measurable quantities are acceptable, how to measure different aspects, what types of measurements might be reliable, and how to appropriately measure using tools they obtain. 

After coming up with a procedure and design, students carry out their experiment in a controlled environment, ideally as part of a class field trip. They then learn to utilize statistics to analyze their data to determine whether what they observed is likely to hold true in a different set of experimenter’s hands. Students also reflect on their experiments in a formal lab write-up as well as a poster presentation. In the end, students present their findings to their peers in a poster presentation during which they have the opportunity to interact with other students’ experiments and ask questions based on their findings as well. 

Lesson 1: Introduction to the Great Cookie Challenge

Lesson Objectives

  • Realize that we are constantly making observations of the world around us and using this knowledge to make everyday decisions.
  • Encourage students to find multiple explanations for observed phenomena.
  • Come up with a process to assess whether our observations of the world are accurate.

Class overview

Before class

  • Print The Great Cookie Challenge introduction packet.
  •  Write on the board: 

How do you know what you know?

During class

As students enter, encourage them to ponder the above question. After a few minutes, ask students to share their thoughts. 

  • Some student responses may consider how one can be sure he or she knows something well:
    • “You can teach it to someone else.”
    • “You can recite it back without thinking.”
  • Some may consider the process by which someone comes to know something:
    • “You evaluate evidence.”- a great response to enable the teacher to segue into the next question:

What is evidence?

Students will likely, perhaps with guidance, identify observations of the world around us as one type of evidence: our five senses provide important information, even measurable evidence. We experience the world through our own existence as a human person (for example, not as an ant or a koala), observing what is presented to us in a human way.

  • From the perspective of modern science, accepting something based on expert authority is tricky. The habit of readily deferring to experts without thinking through the evidence for oneself is contrary to a scientific mindset. If a student proposes that authority is a source of evidence, it can be helpful to encourage deeper reflection. For example, a student may suggest that, “We know something is true if it comes from [someone of authority].” A teacher could reply, “The sky is red.” The class looks aghast at this obviously “untrue” remark, but the teacher repeats, “The sky is red. I experience it as red. It is red. Is this true?” The students are pushed to support why they agree or disagree with this statement. It is easy to disagree based on the wavelength of light that is reflected, which is in the blue band. We can measure this with accurate instruments, and it is blue. For these reasons, there is general agreement that the sky is blue, so it must be blue. However, students who are sympathetic to the claim that someone sees the sky as red may assert: “You are colorblind. That is why you see red.”- Yes! Perhaps the individual cannot sense the light. This is an example of instrumentation error.
  • “The sky IS red….at sunset/sunrise.” Yes! This helps them to see that the way we observe nature is conditional, or based on a certain set of parameters that need to be defined.
  • “You learned the wrong word for the color blue.” Again,this would be an instrumentation error; the observer is calibrated to the wrong vocabulary. This is akin to using metric units when imperial units are given. 

After having discussed how to make observations and assess your observations, the teacher can link this idea to the scientific method. In the scientific method, we:

  • Make an observation.
  • Research the observation.
  • Formulate a question based on considering our observation (developing a hypothesis).
  • Design an experiment to test this hypothesis.
  • Conduct the experiment and analyze the data (make more observations).
  • Discuss what our test showed (conclusions) and other reasons we may have observed this. What other observations were made during the test? 

After this introduction, the class can read through the cookie experiment packet together. As students think about the variables that go into making an excellent chocolate chip cookie, encourage them to discuss what causes a cookie to be this way. How can we test this? In groups, have students discuss how they could test one aspect of the cookie and design an experiment that would empirically examine this aspect. This may take more than one period and can also be assigned as homework. 

Download the Cookie Experiment Packet

About the Author

Kat Hussmann

Science Teacher, Oakcrest School
Dr. Hussmann holds a Ph.D. in Biology from the University of Maryland, College Park, and a Bachelor of Science in Biochemistry and Bachelor of Arts in Spanish from the University of Illinois, Champaign-Urbana. She has done postdoctoral research and has had a number of experiences teaching both college and younger students. She has completed an NIH i...

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