environment has changed. If time allows, a third generation of pancakes can be produced using the same method.
For advanced learners, modifications to this laboratory can easily be made to illustrate more complex evolutionary concepts.
Table 6 presents alterations to the protocol that can be used as
analogies for genetic drift, neutral theory, evidence for evolution,
and cladistics, and instructors are encouraged to develop other
Assessment of the Pancake
Two methods were used to assess the ability of this laboratory to
improve student understanding of natural selection: (1) evaluation
of scores on natural selection questions on examinations, compared
to scores on other topics on the same examinations; and (2) evaluation of student lab reports in which students were asked to write a
Table 6. Example modifications of the standard lab protocol to teach advanced evolutionary concepts.
Concept Modification of Standard Procedure
During the second generation of pancake production, a “surprise” power loss is applied to all but one burner.
As a result, the only pancake produced and, thus, reproduced will be the one from the functional burner.
Neutral theory Neutral theory of molecular evolution suggests that for some alleles there is no selective advantage in variants;
this can be illustrated by shifting from one form of a food to another, very similar, one. For instance, the change
from a Reese’s Cup to a Reese’s Egg or Tree in a blindfolded taste test shows no difference. Students are then
challenged to think about this in the context of human traits with questions such as “Are there traits that vary
from person to person or population to population that do not have any impact on fitness?” This is a springboard
for considerations of how these traits might change over time without the constraints of fitness on frequencies.
After several generations of creating and judging pancakes, students are asked to imagine that the
pancakes they made are preserved in an anaerobic environment for millions of years. Students are then
asked what could be analyzed to reconstruct the evolutionary history of the pancakes. Appearance of
ingredients (phenotype of fossils), chemical analysis of the ingredients (genotype of fossils), and ingredient
geographic distribution through geological time (biogeography) are examples of answers.
After two rounds of making and judging pancakes, introduce the concept of cladistics and guide the
students in constructing clades based on similarities in ingredients.
Table 7. Representative quiz and examination questions, showing the percentage of students answering
the question correctly (n = 78).
Question Students Correct
During the pancake lab, you illustrated natural selection. Match the following components with
the correct natural selection term in questions 1–4:
a. ingredients, b. Pancake Judges, c. pancake batter, d. winning pancakes.
1. Allele variation 94
2. Environment 86
3. Ancestral organism 85
4. Surviving population 100
5. All of the following are correct descriptions of the way that natural selection occurs, except that
a. populations are composed of individuals that have variation in traits
b. individuals change traits during their lifetime, passing on these traits to offspring
c. populations have more offspring than can survive in the environment
d. individuals more suited to the environment survive, passing on their traits to offspring
6. Evolution is a term that is often misinterpreted. Which of the following is the unit that evolves,
or changes, over time?
a. An element
b. An atom
c. An individual
d. A population