Lesson 3: Evidence and Claims

Key Idea

In scientific inquiry, a proposed answer to a specific question is called a scientific claim. For example, stating that "Wind shaped this rock" is a claim. However, in science, a claim is treated as a hypothesis until it is backed up by data.

To validate a claim, scientists must collect evidence. Evidence consists of objective data—such as photographs, measurements, or rock samples—that supports the proposed answer. The validity of a claim rests entirely on the strength and quality of the evidence provided, not on the scientist's opinion.

Key Idea

When making claims about Mars, scientists rely on reasoning based on Earth. The logic follows a specific pattern: "If process X creates feature Y on Earth, then feature Y on Mars was likely caused by process X."

This form of reasoning uses Earth as a model. By finding matching features, scientists gather support for their claims about Martian geology. This allows them to confidently explain events that happened millions of years ago on a planet millions of miles away.