Two 1912 Sources on a New Dam: Sourcing and Corroboration
A class studies a town's 1911 decision to build a hydroelectric dam. The teacher supplies two short documents.
Source A - a promotional pamphlet, 1912, published by a land company developing lots near the dam: "The dam will bring factories, payrolls, and progress. Our town's future is written in concrete and steel. Property values along Main Street have already doubled."
Source B - a letter, 1912, from a farmer whose land lies downstream: "Since the dam went in, the river below it runs thin in July. My bottom field, which used to make sixty bushels of corn, made twenty-two last year. Nobody asked us."
A student concludes: "They disagree, so it's a matter of opinion and both are equally valid."
1. Evaluate how useful each source is for answering "Did the dam benefit the town?" - including what each source cannot show.
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Source A (land company pamphlet):
- Strengths: shows what proponents claimed, what arguments they made, and who was promoting the project.
- Limits: the author profits if lots sell, so claims about factories and doubled property values are advocacy, not measurement. "Already doubled" has no baseline, no date, and no source. This document can tell you what the company wanted people to believe; it cannot tell you whether factories arrived or whether values rose.
Source B (farmer's letter):
- Strengths: a firsthand account from someone directly affected, with specific numbers (60 bushels to 22) that can in principle be checked against farm records. It also documents a process complaint - "nobody asked us" - which is real evidence about how the decision was made.
- Limits: one farm, one year, self-interested (the writer may seek compensation), and the letter never shows the river's flow is caused by the dam rather than by a dry year. It cannot speak to town-wide economic effects.
The key point: the two documents do not contradict each other on a single question. A addresses town-wide development; B addresses one downstream farm. Treating them as opposing sides of one debate is a category error, and it is the error behind the student's "equally valid" conclusion.
2. Write one question each source can answer well and one question each cannot answer at all.
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Source A
- Can answer: What benefits did the dam's promoters promise, and to whom were they selling? (Industry, payrolls, rising property values - pitched to prospective buyers.)
- Cannot answer: Did property values actually double, and did factories actually open? The pamphlet asserts both and documents neither.
Source B
- Can answer: How did one downstream farm's yields change in the year after the dam, and did downstream residents feel consulted?
- Cannot answer: Did the town as a whole gain? One farm's corn cannot measure a regional economy, and it cannot establish that low water caused the drop.
Why this task matters: it forces the distinction between what a source says and what a source can support. Students often accept a source as authoritative for everything it mentions. Naming the unanswerable question is what makes the answerable one meaningful - and it points directly at the records the class would need next (tax rolls, factory payrolls, dam operating records, other farmers' accounts).
3. How would you structure the discussion so students do not land on "both sides are equally valid"? Give the specific moves and the reasoning behind them.
Read the worked answer
Move 1: separate the questions before weighing the sources. Put two questions on the board - "Who gained?" and "Who was affected and how?" - and assign each document to the question it can actually address. The "equal and opposite" framing collapses the moment students see the sources are not answering the same thing.
Move 2: evaluate by position, not by tone. Ask three questions of each source: Who made it? What did they stand to gain? Could anyone check the claim? The land company's pamphlet is not worthless - it is excellent evidence of the sales pitch - but its claims about outcomes fail the checkability test.
Move 3: weigh rather than average. Evidence is not a vote. A single farm's measured yield is weak evidence about the town's economy but strong evidence about that farm, while an unsourced claim that values "already doubled" is weak evidence about anything. Teach students to ask what would settle this? rather than which side do I prefer?
Move 4: name the missing voices. No factory worker, no town official, no other downstream farmer, no dam operating records. Absence of a source is itself a finding about who got to speak in 1912.
The reasoning to make explicit for students: "both are equally valid" feels fair because it sounds neutral, but neutrality about evidence quality is not fairness - it just abandons judgment. The defensible conclusion here is asymmetric: the dam plausibly benefited some residents and harmed others, and the documents let us say who claimed what, not who was right about the total.