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Critical Thinking: Compare, Contrast, and Corroborate

Critical Thinking: Compare, Contrast, and Corroborate

Author: Sophia Tutorial

Identify what it means to compare, contrast, and corroborate sources.

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In this lesson, you will learn about three more of the tools historians use: comparing, contrasting, and corroborating. While you certainly use these tools all the time, you can improve how you use them. Throughout this course in general and this challenge in particular you have opportunities to do just that. Specifically, this lesson will cover:
  1. Introduction
  2. Critical Thinking: Compare, Contrast, And Corroborate
    1. Compare
    2. Contrast
    3. Corroborate

before you start
How have struggles from your past given you strength that you use today?

1. Introduction

In this challenge, we will continue investigating civil rights issues by looking at African American history. Using primary sources and historical analysis, we will consider how Black Americans have struggled for freedom and civil rights throughout U.S. history, and how the fight for equality continues today.

This course focuses on examining the past to identify lessons that we can apply to solve problems today. An important part of that process—and an important task for historians—is identifying cause and effect. Understanding the results of past actions or situations helps us make better decisions in the future.

We’ll also continue practicing the critical thinking process in this challenge. We’ll focus on Step 3 (Application) by looking at specific ways you can put your sources into conversation with one another. One of this challenge’s goals is to learn how to find answers and solve problems when we have multiple sources, some of which may offer conflicting information or perspectives. Toward the end of this challenge, you’ll put the Application step into action as you work on the next part of Touchstone 2.

2. Critical Thinking: Compare, Contrast, And Corroborate

One of the best ways to develop a more complete and accurate picture of the past is to refer to multiple sources.


What you learn from a politician’s private diary entry will be very different from a public political speech, although both could be about the same exact event—and written by the same person.

For historians, more sources of information mean a better understanding of people and events.

Once you’ve found several sources about a historical question you’re investigating, what do you do with that information? Let’s look at the Application step of the critical thinking process, which involves three techniques that will help you use your sources effectively:

  • Comparing
  • Contrasting
  • Corroborating
Graphic of the six steps for critical thinking
Steps for Critical Thinking

2a. Compare
When you compare two or more sources—whether primary or secondary—you’re looking for similarities, and for ways in which they agree with each other.


If you compare several speeches given during the March on Washington for Jobs and Freedom in 1963, you’ll find ways in which the speeches overlap with each other.

They may all mention the same general topic, or the speakers may have used similar speaking strategies to inspire or win support from their audience. Making comparisons can give you a better sense of a historical event as a whole—and having several pieces of evidence that agree can help you build a stronger argument.

2b. Contrast
Of course, sources don’t always agree with one another. As you look at all your sources together, you should also identify the ways they differ. This might mean taking note of differences in the source types, as in our earlier example of a politician’s private diary entry and public speech. But it also means noting where the sources disagree. Primary sources from different perspectives might be telling different parts of the same story—and that’s great, because historians want to know as many sides of the story as possible! Sometimes, though, primary sources might present competing facts. To check these facts, you need to dig deeper. That’s where the third technique comes in.

2c. Corroborate
To corroborate means to use evidence or information from one source to support a statement or finding from another. Remember that historians are investigators. They use sources to gain an understanding of a topic and then they keep going, using even more sources to back up their findings.

When you need to confirm facts from one source, look for that information in more places. Let’s return to our earlier example. If you were researching the March on Washington, you probably wouldn’t just read the speeches that were given that day. You might also look at other sources, such as the event program or newspaper coverage of the march. You would also find secondary sources about the March on Washington, such as a history textbook, a description of the event from the National Park Service, or even a TV documentary.

By using multiple sources to investigate, you can check your facts before you use them as evidence to back up your argument. Here’s another example: the New York Times headline from the day after the March on Washington claims that 200,000 people participated in the march. You could corroborate that fact by checking your secondary sources to see what historians have to say about the number of participants. You could also see what your other primary sources say about the size of the crowd.

Corroboration also has another benefit: it can help you find new stories related to your topic. Say you’re still trying to corroborate the size of the March on Washington crowd. Even if another source doesn’t confirm the number of participants, it might describe experiences of some of the people who were there—a different kind of evidence that helps you understand more about the event. Corroboration doesn’t just help you check your sources; it helps you find new ways to use the information you have.

Problem Solving: Skill Tip
By practicing strong problem solving, you not only can ensure that you are looking at all sides of an issue but you can also better understand and bolster your sources to make a compelling argument. Corroborating information (before you act) in the workplace or even in your family life can help you solve problems faster and more effectively. It can also help you avoid making a decision based on subjective or misleading information!

term to know

To use evidence or information from one source to support a statement or finding from another.
In this lesson, you received an introduction to the next steps of the critical thinking process that you’ll use in this course, as you research sources that will help you to respond to a historical question. When researching multiple sources, the critical thinking process involves comparing your sources to identify similarities, contrasting your sources to identify differences, and corroborating the evidence from your sources by determining whether they support one another.

Best of luck in your learning!


Terms to Know
