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Lesson Plan
Extinction in the Classroom

Daspletosaurus torosus. Catalogue number: CMNFV5806.

Academic Level

Canada-wide: grades 10 to 12
Quebec: secondary cycles 4 and 5


The end of the Cretaceous Period and the beginning of the Paleogene Period is marked by a thin layer of iridium-enriched dark clay. (The time is also known as the K-Pg boundary and the Cretaceous-Paleogene boundary. It was formerly known as the K-T boundary, the K/T boundary and the Cretaceous-Paleogene boundary).

Using images of evidence from the fossil record, students are asked to consider whether dinosaur biodiversity was stable, growing or diminishing at or near the end of the Cretaceous Period, and to identify those species that have successfully survived this 65 million-year-old mass extinction event.

By gaining access to evidence in the fossil record, as well as the results of recent scientific inquiry, students will also evaluate different theories explaining this last great mass extinction event, and have a chance to share and debate their insights with their peers. Extinction in the Classroom provides an opportunity to engage in the ongoing and unresolved debate surrounding the role of extinction in evolution.

Specific Curriculum Links

The following curriculum links are from the Common Framework of Science Learning Outcomes, K to 12, developed by the Council of Ministers of Education, Canada.

To receive the relevant curriculum links for your province or territory's programme of study, write to education@mus-nature.ca.

View the curriculum links.

Grade 10

Life Science Specific Learning Outcomes
Sustainability of Ecosystems

331-6. Analyze the impact of external factors on an ecosystem.

Grades 11 and 12

Life Science Specific Learning Outcomes
Evolution, Change, and Diversity

316-2. Evaluate current evidence that supports the theory of evolution and that feeds the debate on gradualism and punctuated equilibrium.

316-4. Outline evidence and arguments pertaining to the origin, development, and diversity of living organisms on Earth.

Earth and Space Science Specific Learning Outcomes
Earth's Chronology

330-12. Use appropriate evidence to describe the geologic history of an area.

332-4. Illustrate the geologic time scale and compare it to human time scales.

332-5. Compare and contrast the principles of uniformitarianism and of catastrophism in historical geology.

332-7. Describe geological evidence that suggests life forms, climate, continental positions, and the Earth's crust have changed over time.



Preparation time: up to 3 hours
Classroom time: 90 minutes


View the materials list.

  • Computers with Internet connection and Adobe Flash Player (version 8 or greater).

Interactive activity: Declining Diversity

Interactive activity: Winners and Losers

Interactive activities: Gallery Interactives about fossils

Photo: stratigraphic section of the Cretaceous-Paleogene boundary

Photo: shocked and normal quartz

Photo: tektites

Interactive periodic table of the elements


Student Worksheet

Student worksheet: online version

Student worksheet: printable version (answer worksheet) (308 Kb PDF)



Geologic Time Scale (699 Kb PDF)

Chart: Winners and Losers of the K-Pg Boundary (670 Kb PDF)

Map: locations where iridium has been found worldwide (online and printable versions)

Download Adobe Reader 5.0 or greater in order to read PDF-format files.



Consult the reference materials and activities in the lesson plan (interactive activities, photos, diagram, map, etc.).

Familiarize yourself with the terms in the fossil glossary, if needed.

Make sure that the computers in the classroom have no problem opening the interactive activities. You will need the following software:

If you wish, you can print out enough copies of the following documents for the students' groups. Otherwise, they can consult the documents online.
Geologic time scale (699 Kb PDF)
Chart: Winners and Losers of the K-Pg Boundary (670 Kb PDF)
Map: locations where iridium has been found worldwide (115 Kb PDF)

You can also print out enough copies of the student worksheet (308 Kb PDF) for your students to use as answer sheets. They can also answer on other paper. The choice is yours.


Send your students to the online student worksheet to start the lesson (http://nature.ca/education/cls/lp/lpextsw_e.cfm).

1. Observation of the Cretaceous-Paleogene Boundary

Students are shown a photo of a stratigraphic section of the Cretaceous-Paleogene boundary, which emphasizes the thin layer of iridium-enriched dark clay. The layers above the boundary represent the Paleogene Period, while the layers underneath represent the Cretaceous Period. Photos of shocked quartz and tektites are also provided. Students are encouraged to provide their initial thoughts on the origins of the iridium-rich boundary layer.


Suggest that the students take a look at the interactive periodic table of the elements, and find the element iridium and the information about it.

Students must then answer the following questions.

1.1 In what ways does the identification of the element iridium help in determining what may have happened at the K-Pg boundary?

1.2 What could possibly explain the formation of shocked quartz?

1.3 What are tektites and what does their formation suggest about the potential cause(s) of the K-Pg extinction event(s).

Model of a mother Vagaceratops irvinensis and one offspring.

2. Winners and Losers

Students open the interactive activity Declining Diversity. They observe the image of a rock layer from Hell Creek, Montana, U.S.A. This image indicates where specific fossil specimens were found along a cross-section that includes the Cretaceous-Paleogene boundary.

The interactive activity Winners and Losers and the chart Winners and Losers of the K‑Pg Boundary will also help the students answer the following questions.

2.1 Which groups of organisms were able to survive the K-Pg event?

2.2 What proportion of the total number species that was living before the extinction do the surviving species represent?

2.3 Is it possible that there was already a gradual decline in biodiversity among those species that did not survive the K-Pg event?

2.4 Can this assessment be made with certainty, based on the information provided?

3. Comparison of Great-Extinction Theories

Students are divided into groups. Each group will examine the evidence for a different theory explaining the cause of this last great extinction event, 65 million years ago
The theories are:

  • a comet or meteor impact
  • large-scale volcanic eruptions.

Each group is assigned worksheets and references, including the following documents.
They can also consult them online:

Students will also find information in browsing the Gallery Interactives about fossils, from the Canadian Museum of Nature. The K-Pg Globetrotting section presents pertinent information and clues on the separate extinction theories. The clues range from results from prominent scientists to interactive components illustrating supporting evidence for each theory.

Each group presents the most compelling arguments for their given theory. They suggest how this might have resulted in the extinction of a large amount of life on Earth, while the rest was able to survive.

Illustration of a pterosaur of the genus Quetzalcoatlus.

4. Discussion of Extinction Theories

4.1 In a class discussion, analyze the merits and shortcomings of each theory. They are attempting to resolve whether any of them, in isolation, is sufficient to explain the great extinction event that marked the end of the dinosaurs.

Students must answer the following questions.

4.2 Was the K-Pg event perhaps caused by a combination of the factors presented by the student groups?

4.3 Are there other feasible explanations?

5. A Modern-Day Extinction Event?

5.1 Students will pool their newly acquired collective knowledge to ponder the circumstances and results of a speculative modern-day K-Pg event. The original groups are dismantled, and new groups are formed and then tasked with developing and presenting an original scenario outlining the cause, effect and aftermath of a modern-day extinction event.

Students must answer the following question.

5.2 How might this new catastrophe shape the course of evolution?

If you are interested in receiving additional information in support of this workshop, or would like to explore the possibility of a collaboration to extend learning opportunities for your students, you can contact the Canadian Museum of Nature at education@mus-nature.ca.