Using Primary Sources: Nazi Spy Ring Busted

Essential Question

How do historians evaluate the reliability of primary sources to construct an accurate version of historical events?



In this lesson, students watch an excerpt from the Nazi Spy Toys investigation in which they learn about Dr. Fred W. Thomas, a German-American who was accused of being a Nazi Spy during World War II. They then act out the job of the historian by examining primary sources related to the investigation into Dr. Thomas in order to reconstruct an accurate story of Dr. Thomas’s role in the war.

Related Episode: Nazi Spy Toys Investigation

When Jim Wark was growing up in Detroit during World War II, he used to play toy soldiers with Fritz, his best friend and the son of a German immigrant. One afternoon in 1943, Jim learned that a Nazi spy ring had been broken right in his own hometown - and he never saw his best friend again. In this episode, Jim asks host Eduardo Pagan to find out whether his best friend’s dad was, in fact, a Nazi spy.


Suggested Grade Level

This lesson is written for grades 11-12, but can be adapted for use in grades 6-12. Suggestions for adaptation include: limit the number of primary sources and/or highlight the important information in those sources to make the information more accessible; lead students through each of the documents in a whole-class discussion.


Suggested Unit of Study

This lesson is appropriate for American History and World or European History units covering World War II.





Nazi Spy Roundup

Eduardo Pagan searches through microfiche at the public library.

History detective Eduardo Pagan searches through microfiche at the public library in order to find articles related to the Nazi spy ring that Jim so vividly remembers. He finds record of the arrest of Dr. Fred W. Thomas, a German-born obstetrician, and a counter-spy named Grace Buchanan-Deneen. Pagan then provides background on fears of sabotage and espionage during World War II.

Safeguarding Military Secrets

Archive propaganda film - what can happen when the enemy gains access to military secrets.

Fifth Column

President Franklin Roosevelt explains the threat of Nazi spies within the United States.

Viewing station(s) set up with computer(s) and multiple headphones for watching videos. Optional



To view U.S Government Documents slideshow, click here.

To print slideshow, click here.



Determining Bias in Primary Sources 


Estimated Time Required
2 class periods



Though majority of military actions during World War II were fought in the European and Pacific Ocean theaters, there were other theaters of war - including the United States. Nazi spies were conducting intelligence missions in the United States, looking to uncover military secrets and carry out acts of sabotage against American factories, power plants, and other elements of American infrastructure. But American fears about this “fifth column,” or underground group of sympathizers and spies working to subvert the country from within, often led the government to see spies and saboteurs everywhere. American citizens who were members of the Communist party or members of the German American Bund (an organization of German sympathizers) were in danger of being prosecuted as spies, whether or not they were involved in traitorous activities.


Set Up

  • Make enough copies of the reproducible Determining Bias in Primary Sources so that each student has four copies (make copies front to back to save paper).
  • Make a classroom set of copies of the US Government Documents
  • Split the classroom into two stations
  • Document station, with copies of the US Government Documents
  • Video station, with means to watch videos on the internet. (Include headphones. Optional)


Discussion Questions

Have students watch the video “Nazi Spy Roundup” [HD1005-Nazi_Spy_Toys-Web mp4 512.mp4] while taking notes on the following. Afterwards, use the following questions to assess comprehension and prompt discussion:

  • Why would Nazi spies want information about Detroit?
  • Who was Dr. Fred W. Thomas?
  • What did the United States government accuse Dr. Thomas of doing?
  • Who was Grace Buchanan-Deneen?
  • What was the German-American Bund?
  • Make a hypothesis: Was Dr. Thomas a Spy? Or was he caught up in the anti-German paranoia of the time?


After showing the clip Nazi Spy Roundup from the History Detectives episode Nazi Spy Toys, review with students the role of bias in examining historical documents: all documents are biased in some way and one of the keys to understanding primary sources is determining their bias. Bias, you might explain, is where only one side of the issue is being examined and a point of view is based more on opinion and emotion than fact. Explain to students that they will be analyzing primary sources related to the fight against Nazi spies in the United States.

The sources students will investigate include:

  • Fifth Column video: President Franklin Roosevelt explains the threat of Nazi spies within the United States 
  • Safeguarding Military Secrets video: propaganda film showing what can happen when the enemy gains access to military secrets.
  • Department of Justice Press Release about the arrests of Dr. Fred Thomas and Grace Buchanan-Deneen. (U.S Government docs)
  • Government memo recommending against retrial of Dr. Thomas, as he is unlikely to be found guilty (U.S Government docs)

Begin investigation by watching one of the two videos, Fifth Column or Safeguarding Military Secrets. Use the Determining Bias in Primary Sources reproducible to guide a whole-class discussion.

Allow students time to work individually or in small groups to investigate the remaining three primary sources. Encourage the students to “Think Like a Historian” (see this lesson plan for more information on “Thinking Like a Historian). Prompt students to use the following steps when investigating the documents:

  • Sourcing: Who made this source? Where did it come from?
  • Contextualizing: Imagine the setting surrounding this source: How was the world that made this source different than our own?
  • Corroborating: What do other sources say about the information in this document? Do they agree or disagree with what this document says?
  • Close Reading: What does the document say? Is it biased? What is the tone?

Then, reconvene as a class and discuss the students’ analysis of the documents.

  • What bias did you find in these documents?
  • What clues helped you determine that bias?
  • Which document did you find most trustworthy? Least trustworthy?

Give students time to write a response before discussing the following question:

  • Based on these documents, do you think Dr. Fred Thomas was a Nazi spy? Why? What is the most accurate version of events you can tell about Dr. Thomas?

Finally, ask students to evaluate how they were able to arrive at their conclusions when they were given biased documents.

  • How did you evaluate the bias of these primary sources?
  • How do historians construct a version of historical events that is “true”?
  • Can any historical event be reduced to one true story that is based on facts alone? Why or why not?

Going Further

When students have finished investigating the sources related to the Detroit spy ring, direct them to the FBI’s publicdomain documents about other famous spies. Aid students in conducting their own investigation into the biases of these documents. Have students prepare oral reports that summarize the charges against the spy they chose, the biases they uncovered in the documents, and their analysis of the spy’s guilt or innocence.

More on History Detectives

Use the following episodes or lesson plans from History Detectives to support/enhance the teaching of this lesson in your classroom. 







National History Standards

Historical Thinking

1. Chronological Thinking: The student thinks chronologically

2. Historical Comprehension: The student comprehends a variety of historical sources 

3. Historical Analysis and Interpretation: The student engages in historical analysis and interpretation

4. Historical Research Capabilities: The student conducts historical research


US History Content Standards for Grades 5-12

Era 8: The Great Depression and World War II (1929-1945)

  • Standard 3: The causes and course of World War II, the character of the war at home and abroad, and its reshaping of the U.S. role in world affairs


Common Core State Standards

Grades 6-8

CCSS.ELA-Literacy.RH.6-8.1 Cite specific textual evidence to support analysis of primary and secondary sources.

CCSS.ELA-Literacy.RH.6-8.2 Determine the central ideas or information of a primary or secondary source; provide an accurate summary of the source distinct from prior knowledge or opinions.

CCSS.ELA-Literacy.RH.6-8.6 Identify aspects of a text that reveal an author’s point of view or purpose (e.g., loaded language, inclusion or avoidance of particular facts).

CCSS.ELA-Literacy.RH.6-8.7 Integrate visual information (e.g., in charts, graphs, photographs, videos, or maps) with other information in print and digital texts.

CCSS.ELA-Literacy.RH.6-8.8 Distinguish among fact, opinion, and reasoned judgment in a text.

CCSS.ELA-Literacy.RH.6-8.9 Analyze the relationship between a primary and secondary source on the same topic.


Grades 9-10

CCSS.ELA-Literacy.RH.9-10.1 Cite specific textual evidence to support analysis of primary and secondary sources, attending to such features as the date and origin of the information.

CCSS.ELA-Literacy.RH.9-10.2 Determine the central ideas or information of a primary or secondary source; provide an accurate summary of how key events or ideas develop over the course of the text.

CCSS.ELA-Literacy.RH.9-10.3 Analyze in detail a series of events described in a text; determine whether earlier events caused later ones or simply preceded them.

CCSS.ELA-Literacy.RH.9-10.6 Compare the point of view of two or more authors for how they treat the same or similar topics, including which details they include and emphasize in their respective accounts.

CCSS.ELA-Literacy.RH.9-10.7 Integrate quantitative or technical analysis (e.g., charts, research data) with qualitative analysis in print or digital text.

CCSS.ELA-Literacy.RH.9-10.9 Compare and contrast treatments of the same topic in several primary and secondary sources.


Grades 11-12

CCS.ELA-literacy.RH.11-12.1Cite specific textual evidence to support analysis of primary and secondary sources, connecting insights gained from specific details to an understanding of the text as a whole.

CCSS.ELA-Literacy.RH.11-12.2 Determine the central ideas or information of a primary or secondary source; provide an accurate summary that makes clear the relationships among the key details and ideas.

CCSS.ELA-Literacy.RH.11-12.3 Evaluate various explanations for actions or events and determine which explanation best accords with textual evidence, acknowledging where the text leaves matters uncertain.

CCSS.ELA-Literacy.RH.11-12.6 Evaluate authors’ differing points of view on the same historical event or issue by assessing the authors’ claims, reasoning, and evidence.

CCSS.ELA-Literacy.RH.11-12.7 Integrate and evaluate multiple sources of information presented in diverse formats and media (e.g., visually, quantitatively, as well as in words) in order to address a question or solve a problem.

CCSS.ELA-Literacy.RH.11-12.8 Evaluate an author’s premises, claims, and evidence by corroborating or challenging them with other information.

CCSS.ELA-Literacy.RH.11-12.9 Integrate information from diverse sources, both primary and secondary, into a coherent understanding of an idea or event, noting discrepancies among sources.



Grades 6-12

CCSS.ELA-Literacy.WHST.6-12.1 Write arguments focused on discipline-specific content.

CCSS.ELA-Literacy.WHST.6-12.4 Produce clear and coherent writing in which the development, organization, and style are appropriate to task, purpose, and audience.

CCSS.ELA-Literacy.WHST.6-12.9 Draw evidence from informational texts to support analysis reflection, and research.