Fish or Mammals? Argumentation
Background
You have seen several lines of evidence that scientists have used to understand where cetaceans
fit on the animal family tree. In the practice of scientific argumentation, pieces of evidence are used
to support claims. Reasoning is the logical thinking and science ideas that connect claims and
evidence.
Instructions
You will need the following handouts:
• Fish or Mammals? Case study
• Fish or Mammals? Evidence organizer
Using the handouts, find the evidence that connects each claim to the reasoning, and add it to the
table. Keep in mind that a well-substantiated claim may later become evidence or reasoning for
another claim.
For Type of Evidence, fill in whether it is from anatomy (A), embryological development (E), fossils
(F), or DNA (D). (Amino acid sequences, because they are coded in DNA, are DNA evidence.)
In some cases, there are multiple types of supporting evidence.​