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Lesson Plan: Mill Explosion

For Teachers - An Introduction:
This lesson is designed to introduce your students to historical research with primary sources. They will be presented with a set of six primary sources relating to an event in Minnesota history. Your students will be provided with source data, online activity questions to direct their study, and a worksheet designed to help them draw conclusions about the sources they have seen and about conducting primary source research. The units within this site are not offered as comprehensive histories of the people or events involved, but as examples of what students might find in their own research efforts.

The Washburn A Mill explosion in St. Anthony:
In May 1878, the Washburn A flour mill in St. Anthony exploded as a result of flour dust combustion. Eighteen people inside the mill and in nearby buildings were killed in the blast, and much of the surrounding area was leveled. News of this event spread rapidly through the milling industry nationally and internationally. While explosions such as this had happened more frequently in Europe, few of this magnitude had occurred in America. After this explosion, mill owners throughout the country were much more willing to implement new technology designed to reduce the amount of airborne flour dust in mills.

What You Will Need for This Lesson:

  • Access to a computer lab with Internet capability for at least one 40 minute class period.
  • Photocopies of the worksheet and a printed key (download both in the Student Materials section of the site).
  • If you have not already done so, we encourage you to explore the site for yourself ahead of time to become familiar with the navigation and features available to you and your students.

Skills Objectives:
The student will be able to:

  1. access primary sources online for research and study
  2. identify and summarize the different kinds of sources in the exercise
  3. identify advantages and disadvantages to using particular primary sources
  4. explain and synthesize source information to evaluate its usefulness and reliability

Using This Lesson in Your Classroom:
When the students are in the computer lab, instruct them to do the following in this order (you may wish to do this with them on an overhead projector screen):

  1. Go to the Communities web site.
  2. Click on Communities on the left hand side of the screen.
  3. Click on St. Anthony.
  4. Click on Mill Explosion.
  5. Read the introductory material on the mill explosion and click Enter.
  6. This will bring you to a screen with a diagram of a dust collector. This is the first primary source the students will view. Let them know that they can see a larger version of this diagram by clicking on the View button underneath the thumbnail image. Show students the Activity button and have them click on it to view questions and possible answers about each source.
  7. Once students have studied this diagram and read the appropriate questions about it in the Activity section, direct them to the other sources that are accessible through the blue menu bar running across the top of the page. Each of these buttons will take them to a different source to examine.
  8. Remind students to use the Activity button on each source to help direct their research.
  9. When the students have completed studying each source and reading the questions for each item, they should be able to complete the worksheet they were given (see below).

What Your Students Will See In This Lesson Online:
Below is a listing of each source provided on the Mill Explosion section of the web site and a transcript of the activity questions for each source. (These are found on the site by clicking on the Activity button.)

Diagram 1
Click on the Diagram 1 button to open the primary source.
This is a drawing of a machine that was used in flour mills.

    1.1) This machine was used for milling grain into flour. The grain would be put in the hopper at the top of the machine and ground between the two stones in the center of the drawing. Why would a machine that grinds grain need a dust collector?

    Possible Answer:
    This machine has a dust collector installed on it to carry away the dust so it would be less likely to cause a spark. Flour dust can be very combustible, which means that it can explode if the conditions are right.

    1.2) The patent on this machine was given in 1876 and the Washburn A Mill exploded in 1878. What could that tell you about whether this machine was used at the time it was patented?

    Possible Answer:
    The machine may not have been used at first or else it might have prevented the explosion.

    1.3) An engineer who came to the Falls after the explosion had actually talked to the inventor of this machine in 1876. The inventor had been unable to convince people to believe his machine was needed at that time. Why might he not have been able to convince them? Why might that have changed after the mill explosion?

    Possible Answer:
    There had been many mill explosions in Europe, but millers in America had not experienced dust explosions and might not have thought they needed this machine until after the Washburn A exploded.

    1.4) How can a drawing like this help you as a researcher understand a machine or a process better than a written description of the same machine or process?

    Possible Answer:
    A drawing like this allows you to see how the pieces of the machine work together and gives you a clearer idea of how the machine would be constructed and used.

News 1
Click on the News 1 button to open the primary source.
This is an article from the Northwestern Miller that describes the explosion.

    2.1) What possible cause of the explosion does the author disagree with?

    Possible Answer:
    It's been suggested that the explosion was caused by a new process of purifying the middlings.

    2.2) How does the author manage to disprove that theory?

    Possible Answer:
    The reporter suggests that there was a similar mill explosion in Glasgow, where the middlings purifiers were not being used.

    2.3) What does the author suggest could be the actual cause of the explosion?

    Possible Answer:
    Sparks from the milling process and grind-stones could ignite the flour dust in the mill and cause an explosion.

    2.4) Describe the experiment used to test for the explosiveness of flour.

    Possible Answer:
    Flour is puffed with air into a box by using a bellows. The flour/air mixture is ignited. The force of the explosion is measured by measuring how far a smaller box stuck into a vent is thrown.

News 2
Click on the News 2 button to open the primary source..
This is an article from Popular Science Monthlythat explains how flour dust can cause an explosion.

    3.1) This article is actually the transcript of a lecture given a month after the mill explosion. It presents one possible reason why the mill exploded. How do these experiments on the topic affect your opinion of the author's work?

    Possible Answer:
    This author provides scientific knowledge of why the mill exploded, which makes his work more reliable than the work of someone who had not done any experiments.

    3.2) The speaker who gave this lecture was asked by a milling association to speak on this topic. Why do you think his information might be especially interesting to the members of this association?

    Possible Answer:
    The millers would want to be able to learn ways to prevent explosions in their own mills in the future.

    3.3) The writer describes how fires can be started if the "feed" goes off, meaning if the grain stops feeding into the grinders. How might fire result from this?

    Possible Answer:
    The millstones would have no wheat between them. This could cause sparks to fly. Even simple sparks could be enough to cause an explosion if the air is full of flour dust.

    3.4) From this article, can you tell if the "A" mill explosion was the first of its kind?

    Possible Answer:
    You can tell that it was not the first. The article states that these explosions have been happening in Europe, but that they were less frequent in the United States.

Art 1
Click on the Art 1 button to open the primary source..
This is a drawing that appeared in the American Miller magazine in June of 1878. This drawing shows the scene of the Washburn A Mill explosion in Minneapolis.

    4.1) What details can you learn about the event from this source?

    Possible Answer:
    This source can give you an idea of the amount of damage the explosion caused and how it affected surrounding buildings.

    4.2) What kinds of information does this source not provide for you about the event?

    Possible Answer:
    This source does not tell us anything about the cause of the explosion or who might have been injured or killed.

    4.3) What details in this source can give you hints about when this event took place?

    Possible Answer:
    The clothing of the spectators, the fact that they are on horses and use umbrellas and baby carriages all suggest that this event occurred in the late 19th century. This could be verified or proven by looking at sources that would show fashions at that time, such as magazines or mail-order catalogs.

    4.4) What about this drawing might suggest that this event had an impact beyond Minnesota?

    Possible Answer:
    The drawing was published in a national paper.

Map 1
Click on the Map 1 button to open the primary source.
This is a map from the Northwestern Miller magazine of the area around the explosion and the other buildings that were affected.

    5.1) How many buildings other than the Washburn A Mill were damaged when it exploded? Looking at the map, what other structures or features might have been damaged also?

    Possible Answer:
    Ten other buildings were damaged by the explosion. By looking at the map, you can also see that railroad lines, streets, and a covered canal might have been damaged.

    5.2) How could a map like this allow you to better understand other sources about this event that you might find?

    Possible Answer:
    The labels on this map can help you identify buildings in photographs and the location of the area around the explosion with more accuracy.

    5.3) As a researcher, this map can be helpful in many ways, but what things does it NOT tell you about the event?

    Possible Answer:
    This map does not tell you the cause of the destruction or if anyone died or was injured or whether the damage was done by fire or explosion or something else.

    5.4) This map gives us a diagram of the location of the explosion and a compass rose to show us directions. What other map features would have been helpful for us?

    Possible Answer:
    The map does not give us a larger view of where in Minneapolis the event happened. It also does not label the river (it's on the right side of the map) or give us a clear indication of how large the burned buildings were.

Photo 1
Click on the Photo 1 button to open the primary source.
This is a page of photographs from The Eventually News that shows the men killed in the mill explosion.

    6.1) What in these photographs might suggest to us that these were posed and not "candid" shots?

    Possible Answer:
    All of the men are dressed up in the photographs and seem to be posed in front of some kind of photographer's backdrop or curtain. If these were candid photographs, we might see them at work or outdoors and in more casual clothing.

    6.2) This collage of photographs was published years after the explosion in a memorial edition of a newspaper. Why do you think the newspaper would have published an issue about the event so many years later?

    Possible Answer:
    The explosion had a great effect on the people and community of Minneapolis at the time. Newspapers or magazines often publish or republish accounts of significant events in memorial editions. Occasionally new information about the cause of the event is discovered, or it may just be the anniversary of the event and the newspaper wanted to honor those who died in the explosion in this way.

    6.3) Fourteen of the men killed worked in the Washburn A Mill at the time of the explosion. What does the fact that four people in neighboring mills also died tell you about the power of the explosion?

    Possible Answer:
    The fact that four workers in other mills also died shows us that the force of the explosion was very strong and also that debris could have been thrown a great distance.

    6.4) What can these photos tell you about hair and clothing styles at the time?

    Possible Answer:
    Beards were popular, as well as mustaches. Short hair was fashionable for men. Bow ties and suit jackets were worn for formal photographs.

Thought Questions for Online Exploration:
During the online lesson, your students should complete the accompanying worksheet for this section. (Download from the student materials the pdf file containing the worksheet and key.) The questions for this worksheet are provided below. Since questions relating to specific sources are used during the online activity, the following worksheet questions are designed to help students synthesize and apply the material they have learned from the online activity and to analyze the kinds of information and the credibility of various types of primary sources when taken as a whole.

  1. Occasionally newspapers will publish "memorial" or commemorative editions of their newspapers to mark the anniversary of an important event. Often these editions will include reminiscences by people who either were involved in the event or had family members who were involved and passed the story down to them. As an historian, how can a commemorative edition be a useful source? How can a reminiscence of an event written years later be different from what someone might have written about an event immediately after it happened? How can that affect the reliability of the source? What other sources might help you support the statements in newspaper commemoratives?

  2. Immediately after an event such as an explosion, many people theorize (make their best guesses) about the cause of the event. After the mill exploded, many people had different theories about why it happened. How can you as an historian evaluate these theories about an event? Since modern technology and scientific thought may have already explained a past event completely, what can you do to get into the "mindset" of people at that time and use the resources they would have had to evaluate the event itself? How can being able to do this help you get a better understanding of the people and events at that time?

  3. Newspapers often published drawings or maps after events like this to give their readers a clearer picture of what happened and the impact an event may have had. How can these sources help us as historians today? What can we do to evaluate how reliable and accurate a map or diagram might have been? In what ways can even an inaccurate map or diagram be of help to us?

  4. Tragedies often are portrayed in the media by showing photographs of the lives lost. During the Gulf War, many of the major news magazines published pages of photographs of those who died in the fighting. The Eventually News published photographs of those who died in the mill explosion. Aside from providing simple information, what can photographs like this do for the reader of the article? How can the media influence our thinking about an issue by using our emotions? How is this done in other ways today? How effective do you think this is? As a historian, how can you evaluate and use sources that bring out the reader's emotions?

Extending the Lesson: Historical themes in the mill explosion
You can also use the sources provided on this site to encourage higher-order thinking about a number of historical themes and issues that relate to to the Washburn A Mill explosion. Below are possible activities and discussion starters to extend student application of the content material provided in the sources. The information provided in the sources about mill explosion does not give us a comprehensive picture of these issues, but it can serve as an introduction to a theme or as supplementary material to enhance your work with a theme that is already part of your curriculum.

Possible Themes:
1. Technology and Safety
2. Dealing with Tragedy

Theme One:
Technology and Safety

The student will be able to :

  1. describe and explain the role of safety in occupations
  2. evaluate conflicting accounts of an event for accuracy
  3. examine the effects of tragic events on a community or group
Class discussion:
Ask students to discuss the following questions in small groups or as a class.

  • What kinds of safety measures are taken in your school to keep you from getting hurt while you are here? What does your school do well in protecting you from injury and what do you think your school could improve?

  • When something happens in school (a student gets injured in a sporting event or a class) what do you hear about the event at first? How reliable do you think those accounts might be? How do you eventually find out what really happened?

  • Describe two or three jobs held by adults you know. What kinds of dangers might they face in their jobs? What do their companies do to protect their employees? What would happen if they were injured on the job and unable to work?

  • What job would you like to have when you leave school? What do you think your working conditions will be like? What kind of safety training might you need if you worked with heavy equipment like the millers in St. Anthony?

  • Do you think the Washburn A Mill owners could have prevented the explosion? Why or why not? What might have been the company's reasons for not doing things that might have prevented the explosion?

Optional activities:

  • Have students choose an event (local, national, or world) that they remember as tragic. Either in groups or individually, ask them to consider these questions about the event. Have them present their thoughts to the class in an oral report. How was the event portrayed in the media? What theories about its causes were offered immediately after the event happened? How accurate were those theories? What do we know now about the event that we didn't know then and how does that change our interpretation of the event? You might ask students to choose a current event and speculate as a class about how accurate our current media portrayalis.

  • Ask students to choose a safety issue they currently encounter and design an invention to make themselves more safe (for example, a machine that won't let a car start if the driver is drunk). Have them prepare pictures and a description of the invention and describe it to the class. How would they go about producing such an invention? What materials would they need to manufacture it? How much do they think it might cost? How would having this new invention improve their lives and their community?

  • When tragic events like the mill explosion occur, families often are left with bills and debts that they are unable to pay. Organize a food or charity drive in your class to donate goods to a local food shelf or relief organization. Have students make a class list of other things they can do to help people in need and post it in your room.

Theme Two:
Dealing with tragedy

The student will be able to:

  1. describe how people deal with and survive tragedy in their community
  2. describe and evaluate local and national plans for dealing with tragedy
  3. develop ways to help those who are dealing with tragedy
Class Discussion:
Either as a class or in small groups, have students discuss and record their answers to the following questions. If you are doing these in small groups, discuss them as a class after the groups are finished.

  • When a tragedy like the mill explosion hits a community, many things can either make it easier or more difficult for the town to survive the tragedy. What actions by a community's citizens can help the community recover? What actions are not as helpful? What role might the community leaders, media, and service personnel play in helping the recovery?

  • Describe and discuss a national or world event that you would consider a tragedy. What things were done to help those affected recover? What role did the government play in recovery? What things might you have done to help?

  • Tragedies often teach us much about ourselves, our community, and our world. What kinds of things can we learn from a tragedy once we have recovered? What kinds of changes might we want to make to ensure that the tragedy doesn't happen again?

Optional Activities

  • Have students study a recent tragedy in the news. What were the immediate effects of the tragedy? What might be the long-term effects felt by those who were involved? How can those who were impacted by the tragedy be helped to recover? Have students study the news accounts of the event and evaluate how well they think the event was handled and report to the class. Ask students to state both the good things that were done to handle the tragedy and the areas where things might have been improved. Ask them also to consider how accurate their interpretation might be of the event since they were not present at the time.

  • Invite a school psychologist, local minister, or counselor to class to describe how people react when faced with a tragedy. Ask the guest to explain practical ways in which students can help. You might ask the guest to teach students some basic listening skills or crisis management techniques (whom to call, etc.).

  • Encourage students to chose a major tragic event in world history (sinking of the Titanic, earthquakes, tornadoes, airplane crashes, etc.) and study the event. What efforts were made to help the survivors (if any)? What role did the governments involved play in the recovery? What effects did this event have on the families of those killed? What did other community members do to help? Students should report to the class.

  • Organize a class project to help victims of a current tragedy. Students could increase awareness of the event through posters or school newspaper articles, collect food for a food shelf or stage a clothing drive, write letters to their legislators asking for government aid for the crisis (famine relief, etc.), or make cards of support to mail to victims of the tragedy.

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