Fellow name: Sara Painter Title of Lesson: Becoming Whale Grade ...

Fellow name: Sara Painter
Title of Lesson: Becoming Whale
Grade Level: 7 th grade Life Science
Subject(s): Evolution – evidence for change over time
Summary:
This lesson is designed to give students a firsthand experience of how scientists use the
fossil record to generate ideas about the evolutionary history of modern day species. The
lesson has two parts. In part one the students will be gather information that will allow
them to discover who were the ancestors to modern day whales and what evolutionary
transitions occurred as whale evolved from land dwelling to marine mammals. The students
will “dig” through cups (soil layers) and discover fossils. They will use a combination of
information including the laws of superposition, radioactive carbon dating and intuition to
generate a hypothetical phylogeny of whales. In part 2 the students will see how the
evolution of whales fits into the larger geologic time scale. The students will create a time
scale with their bodies starting from the formation of the earth and ending with modern
human civilization. Each student will received a major event in earths history and a time
point and they will need to form a big circle around the classroom standing in the correct
order.
Time required/planned for:
Part 1
- Introduction 20 min
- Lab activity 30 min
- Review 10 min
Part 2
- Geologic time scale activity 15 min
- Rap Up 15 min
Group Size:
2-4 students per group

Cost to implement:
- Each group will need:
o Eight plastic cups (~$0.50)
o Several copies of each skeleton type (one per student)
o Tape (~$2.00)
o Worksheet (one per student)
Learning Goals:
- After this lesson students should:
o understand how fossils provide evidence for the evolutionary history of
animals
o have improved ability to build and interpret branching tree diagrams
o be able to describe how the Cambrian explosion got its name
o be able to put major events in earths history in the correct order
Level of Inquiry:
- Students will be investigating the answer to the question “who were the ancestors of
modern day whales?”
- The students will first make hypotheses and predictions regarding the characteristics
they would expect a whale ancestor to have.
- They will then gather evidence by discovering fossils and using the law of
superposition to place each skeleton on the timeline to create the history of whales.
The students will not be given the correct answer and will need to argue with their
classmates about which tree is the best and why.
Introduction / Motivation:
This lesson will be introduced using a power point presentation. At the beginning of the
presentation show pictures of some whales and dolphins and ask the students to identify
what they see. Ask students to discuss with their neighbors and write own three
characteristics that all whales share. Have a class discussion about their answers. Lead the
students through a logical argument that whales are mammals and thus, share
characteristics with other mammals (some of the students may have come to this
conclusion already). Now explain that we know from fossil evidence that mammals evolved
on land and thus, we can conclude that whales must have evolved from land mammals as
well.
Next introduce the following question which will be the basis of the lab investigation:
- How did whales evolve from land mammals?
Before explaining the lab activity I will ask the students/we will discuss the following:
o What kind of evidence would you need to answer this question?
o Answer: Fossils of intermediate forms showing a transition from a life on land
to a life in the water in their skeletal structure.
Next ask the students to make some predictions, based on what you have discussed this
far, regarding the characteristics they would expect a whale ancestor to have.
- To aid their thinking display the following diagram via powerpoint and ask the
students to make prediction about what should go in the question mark spaces.

Now introduce the lab activity by reading the following paragraph while they follow along on
their worksheet:
Imagine that you are an archeologist. Together with your team
of scientists you are trying to answer the following question:
How did whales evolve from land mammals?
To answer this question you and your fellow scientists spent
several years excavating skeletons of animals you believe to
be possible ancestors to modern day whales. You have
brought these skeletons home to you lab for closer
examination. The approximate dates of each fossil have just
come back from the radioactive dating lab. Now you will use this data to reconstruct
the history of whales on the timeline provided.
Procedure:
Part 1 Lab:
Set up and instructions:
Set up several lab stations around the classroom such that there will be no more than four
students per group. Each station will need eight plastic cups labeled A, B, C…H. The cups
should be stacked so that A is on the top and H is on the bottom. In each cup should be the
following skeleton species.
A = Tursiops and Eubalana
B = Zygorhiza
C = Physter and Balenoptera
D = Diorocetus
E = Ambulocetus
F = Durodon and Basilosaurus
G = Diacodexis
H = Indohyus and Pakicetus
Each lab station should also have a copy of the radio active dating table below:

Activity:
Soil Layer (cup) Time Period (mya)
A 5-11
B 26-32
C 12-18
D 19-25
E 40-46
F 33-39
G 54-60
H 47-53
Starting with cup A students should “dig” for fossils. Each student should get one copy of
every fossil type in the cup (soil layer). They will then need to use the table of radio activity
dating of each soil layer to find out which time period the fossil is from. Using this
information they should put the fossil in the correct empty box on the timeline on their
worksheet. By the end of the lab each box should have a whale fossil. Once the students
are satisfied with the timeline they have created have them tape down each of the whale
fossils.
Part 1 Closure:
When the students are finished collecting and graphing their data lead the class through a
discussion by asking them to reconstruct the phylogeny of whales using the evidence they
collected. Draw a timeline up on the white board, identical to the one on their worksheet.
Print out larger versions of the 12 skeleton types. Have student volunteer to tape the 12
skeletons up on the board in the location they think it should be. Once all the pictures are
taped on the board ask the class whether they agree or disagree with the whale history on
the board. Ask those who disagree to explain where and why. For any discrepancies
pointed out by the students take a class vote on how the tree should be rearranged. Move
any necessary skeletons to as direction by the majority vote.
Do not tell the student the correct answer, but instead use this as a platform to launch a
discussion about how scientists can never know the correct answer regarding evolutionary
relationship between fossil organisms. Explain how scientists have to take their best guess
given the information provided. Explain the problems with using the fossil record and the
many ways in which it is incomplete.
Part 2
set up instructions:

Create a timeline around the classroom by taping large number 0, 100, 200,….1000 around
the classroom at roughly equally spaced intervals. Print out the major events in earth’s
history and cut them into strips.
Activity:
Randomly hand out one strip of paper to each of the students. Explain that they will be
recreating the geological time scale using the major events in earth’s history. Explain that
instead of speaking in millions and billions of years (abstract concept) that you have
recreated the time scale to be more familiar. 1000 is the beginning of our planet and the
time the earth was formed. 0 is today. Have the students find their appropriate position on
the time scale tapped up around the classroom.
The majority of the students should be clustered between the 100 and the 0. Stop them
and ask why they are so clustered and crowded together. Explain to the student that this
actually what earth’s history looks like. It begins with long expanses of time were not much
happened. In fact, this is most of earth’s history. It is only recently, after the Cambrian
explosion, when most of the stuff we consider to be interesting happened.
Now, for the sake of elbow room, have the students ignore the time scale taped around the
room and instead spread out to form a nice complete equally spaced circle. Starting with
the formation of the earth have each student read their major even in earth’s history and
the relative time point.
One the students have returned to their seats use the last power point slide to emphasize
and discuss what they just discovered.
Is this lesson based upon or modified from existing materials? If yes, please
specify source(s) and explain how related:
Yes, I modified a lesson on whale evolution that I found online:
http://www.indiana.edu/~ensiweb/lessons/whale.ev.html
References:
Evolution of cetaceans:
http://en.Wikipedia.org/wiki/Evolution_of_cetaceans
The origin of Whales and the power of Independent Evidence
http://www.talkorigis.org/features/whales
Attachments:
- Becoming whale worksheet
- Becoming whale powerpoint
- Major events in earths history
- Mini and large whale ancestor fossils
- Numbers 0-1000

List CA Science Standards addressed:
Evolution:
3.c. Students know how independent lines of evidence from geology, fossils, and
comparative anatomy provide the bases for the theory of evolution.
3.d Students know how to construct a simple branching diagram to classify living groups of
organisms by shared derived characteristics and how to expand the diagram to include fossil
organisms.
Earth History:
4.e. Students know fossils provide evidence of how life and environmental conditions have
changed.
4.g. Students know how to explain significant developments and extinctions of plant and
animal life on the geologic time scale.