Case Study 2 — Pat Hammond's Biotechnology Unit

The classroom

Pat Hammond teaches AP Chemistry and General Chemistry at the public high school in her town in rural Ohio. The town has about three thousand residents. The high school graduates roughly seventy students a year. Pat has been teaching there for twenty-eight years. She has a folder of "demonstrations that work," which she has been building, refining, and pruning for almost three decades. The folder is, by her own admission, the most valuable professional asset she owns.

In 2018, Pat added a new unit to her AP Chemistry curriculum: a four-week unit on biotechnology, with a particular focus on food applications. The unit was, at the time, a response to a specific frustration. Her students — sixteen-year-olds in a community where many of their parents farm — were encountering biotech in the news constantly (CRISPR, GMOs, "lab-grown meat," "the Impossible Burger") and were getting their information almost entirely from sources that were either marketing or alarmism, with very little science in between. Pat decided her students deserved to learn the chemistry well enough to evaluate the claims for themselves.

This case study is about the unit Pat built, what worked, what did not, and what she learned about teaching food biotechnology to teenagers in a community where the topic has political weight.

Week one: the chemistry foundation

The first week of the unit Pat does without any biotech examples at all. She reviews enzyme chemistry — substrate, product, active site, induced fit, the Michaelis-Menten equation in basic form — and she has the students do a hands-on lab with a familiar enzyme.

The lab she uses is a classroom version of the chymosin demonstration: students are given small samples of warm whole milk and varying concentrations of vegetarian rennet (microbial chymosin from a cheesemaking supplier; available online for under twenty dollars for a quantity that supplies a class of thirty), and they observe and time the curd formation as a function of enzyme concentration. The data fits a textbook saturation curve. At very low concentrations, doubling the enzyme nearly doubles the rate. At high concentrations, doubling the enzyme barely changes the rate (substrate is now limiting). The students plot their data, fit a curve, and discuss what would change with different temperatures, different milk pH, and different enzyme batches.

The lab takes one ninety-minute class period. It costs about thirty dollars for a class of thirty students. It demonstrates enzyme kinetics with kitchen-grade equipment. And it has the property — Pat says this is what she values most — that every student understands the lab. There is no student who is left behind by the chemistry, because the students can see the curd forming with their own eyes.

⚠️ Allergen flag in classroom. Dairy. Students with milk allergy or severe lactose intolerance should not handle the milk samples. Pat's school provides almond-milk equivalents (which do not curdle with rennet — itself a useful demonstration) for those students.

Week two: production

The second week is about how the rennet enzyme is produced at industrial scale. Pat uses a video tour of an enzyme-production facility (Chr. Hansen and Novozymes both have public-facing educational videos, as does the educational arm of the American Society of Microbiology). She walks the students through the basics:

• The enzyme is produced by a genetically engineered organism — typically a fungus (Aspergillus niger) or a yeast.
• The organism's genome has been augmented with a gene from calf chymosin, inserted by recombinant DNA techniques.
• The organism is grown in a large fermenter (similar in principle to a brewery fermenter), under controlled temperature, pH, oxygen, and feedstock conditions.
• The enzyme is secreted into the growth medium, then separated from the cells, purified, and concentrated.
• The final product is a clear or pale yellow liquid (or a powder for shipping stability), containing essentially pure chymosin enzyme. No genetically engineered DNA is present in the final product.

The students do not need to memorize the entire process. The point Pat wants them to understand is the separation — that the engineered organism is in the fermenter, and the molecule that ends up in the cheese is not the organism but a pure protein that the organism produced. This is the key conceptual move that distinguishes precision fermentation from "genetically modified food" in the conventional sense.

For homework, Pat assigns students to bring in any cheese product from their family's refrigerator. They are asked to read the ingredient label and find the rennet listing (it may say "rennet," "vegetarian rennet," "microbial enzymes," or sometimes just "enzymes"). The next day, the class compiles the data: what fraction of the cheeses in their refrigerators were made with each kind of rennet? In Pat's classroom, year after year, the answer is approximately eighty to ninety percent recombinant or microbial. Most students have eaten precision-fermented cheese for their entire lives without knowing it.

Week three: the wider technology landscape

The third week is the broadest. Pat covers the categories of food biotechnology — precision fermentation (chymosin, insulin, vitamins, dairy and egg proteins), cultured meat, microbial protein (Quorn, Solein), CRISPR-edited crops, plant-based meats — with a mix of lectures, readings, and short assignments.

For each technology, she asks the students to research and answer five questions:

1. What does it produce?
2. How does it work, mechanistically?
3. What is currently at commercial scale, and what is still in research?
4. What are the strongest claims its proponents make? Are they supported?
5. What are the strongest concerns its critics raise? Are they supported?

The students give five-minute presentations on assigned technologies. Pat evaluates them on technical accuracy and on epistemic honesty — whether they distinguish what is known from what is contested, whether they cite sources, whether they handle the values questions without sneering at people on either side.

Pat says this is the part of the unit where she has had to be most careful. Her students come from families with strong opinions on biotechnology — some farm families are enthusiastic about new tools, others are deeply skeptical, and a few are politically aligned with anti-GMO advocacy. Pat's principle is that she does not tell the students what to believe; she teaches them to read the evidence. The goal is that any student, regardless of family background, can leave her class able to evaluate a biotech claim on its merits.

Week four: the values discussion

The fourth week, Pat says, is the one she had to figure out by trial and error.

For the first two years of the unit (2018, 2019) she ended the unit with a final lab and an exam. The students did well on the exam. But Pat noticed that something was missing — the students had absorbed the chemistry, but they had not, as a class, talked about the harder questions. The values questions. Whether food sovereignty matters. Whether displacing smallholder farmers with lab-grown alternatives is a problem we should worry about. Whether GMO labeling should be required, even when the chemistry is identical. Whether the "future of food" should be designed by the same kinds of institutions that designed the present of food.

Starting in 2020, Pat added a structured discussion week. The discussions are based on a set of cases she has built up — short scenarios, often based on real-world events, that put the students into the position of having to make decisions where chemistry alone does not give the answer.

A representative case: A multinational food company has developed a precision-fermented cocoa replacement that produces a product similar in flavor and chemistry to conventional chocolate, at one-third the carbon footprint. The technology is ready for commercial scale. If it succeeds, it could replace as much as half the global market for cocoa-bean-based chocolate within fifteen years. The company is headquartered in Switzerland. The smallholder farmers who currently grow cocoa — about five million households worldwide, mostly in West Africa, but also in Latin America and Southeast Asia — depend on cocoa for a significant fraction of their income. Many of these farmers are food-insecure. The company has announced no transition support for the displaced farmers.

The students are asked, in groups of four, to take positions: as the company, as the displaced farmers, as a regulator in a cocoa-importing country, as a regulator in a cocoa-exporting country, as a consumer. They argue. Pat does not tell them what the right answer is. She does insist that they ground their positions in evidence and that they engage seriously with the strongest version of the opposing view.

What Pat reports, and what makes her keep teaching the unit, is that students get genuinely good at this discussion. By the end of the four weeks, the students who started the unit with strong family-inherited positions on either side of biotechnology have, almost without exception, become more nuanced. Not because Pat told them to. Because the evidence, presented carefully, supports nuance — and because their classmates (some of whom started from very different places) made arguments they had not previously encountered.

What Pat learned

Pat told me, when I asked her what she had learned from teaching the unit, that the lesson was not really about biotechnology. It was about how to teach a politically charged scientific topic in a community where the science gets mixed up with the politics.

The principles she has settled on:

• Start with the chemistry, not the politics. If the students understand enzyme kinetics and protein purification, they have a foundation that does not depend on whose team they are on.
• Use the students' own kitchens. The cheese-rennet survey makes the abstract concrete. Most of them have already been eating precision-fermented food for years; recognizing this changes the conversation.
• Distinguish what is known from what is contested. Pat is explicit, every class, about which claims are well-supported by science and which are still open. The students learn to make this distinction themselves.
• Do not tell them what to believe. The students leave Pat's class better at evaluating biotech claims, but they do not all leave with the same conclusions. Pat counts that as a success.
• Do address the values questions. Pretending the values questions do not exist, or dismissing them as "not science," is a failure of teaching. The values questions are real, and the students will encounter them outside of class. They deserve practice handling them with care.

What this case tells us

This case is about the educator's perspective on the future kitchen — and about what it takes to teach the topic well in a community that has reasons to be skeptical of any "innovation" framed by people far away.

It also illustrates what we have argued throughout this chapter: that the science of food biotechnology is mostly chemistry that is already familiar — enzymes, proteins, fermentation, cellular biology — and that understanding the chemistry is the prerequisite for evaluating the claims. A community of students who understands enzyme kinetics is a community of citizens who can read a press release about a new food product with their own eyes.

That is, perhaps, the most useful future-of-food technology there is. It is not in any laboratory. It is in any classroom where a teacher has decided to teach the chemistry honestly and to trust the students to handle the rest.

Analyze this

You are designing your own four-week unit on food biotechnology for a high school chemistry class.

1. What chemistry foundations would you cover before introducing biotech examples? Justify your choices.
2. Which biotechnologies would you cover, and in what order? Should you start with the technology that is most transparent (precision-fermented chymosin) or the one most relevant to students' food landscape (plant-based meats, perhaps)?
3. Pat handles the values questions in the fourth week, after the chemistry is solid. Some teachers would integrate values throughout. Which approach do you think is better, and why?
4. The unit Pat teaches assumes a politically diverse community where the topic is sensitive. What would you change if your community were more uniform in opinion? More urban? More rural? More ethnically diverse?
5. Pat reports that her students become more nuanced over the unit. Is "more nuanced" always a desirable outcome of education? Are there topics on which "more nuanced" might be inappropriate? Where does food biotechnology fall on that spectrum?