Overview

Lesson Procedure

65-75 minutes of class time across 5 phases.

1. Warm-Up5-10 minutes
2. Direct Instruction25 minutes
3. Guided Practice15 minutes
4. Independent Practice15-20 minutes
5. Closure5 minutes

1. Warm-Up5-10 minutes

   Warm-Up Prompt

   "Your weather app shows a 10 percent chance of rain. Out the window, the sky is dark. A friend walks in with a wet jacket. You are about to leave for a two-hour walk. Do you take an umbrella? Which source decides it, and what do you make of the fact that they disagree?"

   Take a quick vote, then ask students to explain the disagreement rather than just pick a winner. The app may describe a whole region for the whole afternoon; the friend's jacket describes one street a few minutes ago. Then add a twist: "What if the app had predicted rain every day this month and been wrong every time?" Tell students that SL.11-12.2 asks them to integrate sources in different formats in order to decide something, and to treat each discrepancy as information. Today's case shows what happens when a warning has been wrong too often.

2. Direct Instruction25 minutes

   Part 1: What grades 11-12 add. The 9-10 standard asks students to integrate sources and judge each one. The 11-12 standard adds a goal, "to make informed decisions and solve problems," and a duty, "noting any discrepancies among the data." A discrepancy is any place where two sources, or a source and its own numbers, disagree. Students record each one in a log with a column for what it means for the decision.

   Discrepancy log: four kinds of discrepancy (SL.11-12.2)

   Kind of discrepancy	Typical cause	What to do before deciding
   Explained	The sources measure different things, places or times	State the difference and use each source for what it measures
   Error	One source miscounts, misquotes or overstates	Correct it from the more credible source and lower your trust in the source that erred
   Exception to a pattern	A case that does not fit the main explanation	Look for a reason the case differs; an explained exception can strengthen the pattern
   Unresolved	No source on hand settles it	Name the evidence that would settle it and say whether the decision can wait for it

   Part 2: The dam and the warnings. Above Johnstown, a private club owned an old reservoir dam and the lake behind it. Johnson's book was published in 1889, the year of the flood; it collects statements from many people, some written, many first spoken to reporters. Read the two passages aloud. Paragraphs are numbered.

   1When the Hunting and Fishing Club bought the site of the old reservoir a section of 150 feet had been washed out of the middle. This was rebuilt at an expense of $17,000 and the work was thought to be very strong. At the base it was 380 feet thick and gradually tapered until at the top it was about 35 feet thick. It was considered amply secure, and such faith had the members of the club in its stability that the top of the dam was utilized as a driveway. It took two years to complete the work, men being engaged from '79 to '81. While it was under process of construction the residents of Johnstown expressed some fears as to the solidity of the work, and requested that it be examined by experts. An engineer of the Cambria Iron Works, secured through Mr. Morrell, of that institution, one provided by Mr. Pitcairn, of the Pennsylvania Railroad, and Nathan McDowell, chosen by the club itself, made a thorough examination. They pronounced the structure perfectly safe, but suggested some precautionary measures as to the stopping of leaks, that were faithfully carried out. The members of the club themselves discovered that the sewer that carried away the surplus or overflow from the lake was not large enough in times of storm. So five feet of solid rock were cut away in order to increase the mouth of the lake. Usually the surface of the water was 15 feet below the top of the dam, and never in recent years did it rise to more than eight feet. In 1881, when work was going on, a sudden rise occurred, and then the water threatened to do what it did on this occasion. The workmen hastened to the scene and piled débris of all sorts on the top and thus prevented a washout.

   2For more than a year there had been fears of a disaster. The foundations of the dam at South Fork were considered shaky early in 1888, and many increasing leakages were reported from time to time.

   [...]

   3Confirmation has certainly been had at South Fork, Conemaugh, Millvale and Johnstown. The rumor of an expected break was prevalent at these places, but citizens remarked that the rumor was a familiar incident of the annual freshets. It was the old classic story of "Wolf, wolf." They gave up the first floors to the water and retired upstairs to wait until the river should recede, as they had done often before, scouting the oft-told story of the breaking of the reservoir.

   1According to the statements of people who lived in Johnstown and other towns on the line of the river, ample time was given to the inhabitants of Johnstown by the railroad officials and by other gentlemen of standing and reputation. In hundreds of cases this warning was utterly disregarded, and those who heeded it early in the day were looked upon as cowards, and many jeers were uttered by lips that now are cold. The people of Johnstown also had a special warning in the fact that the dam in Stony Creek, just above the town, broke about noon, and thousands of feet of lumber passed down the river. Yet they hesitated, and even when the wall of water, almost forty feet high, was at their doors, one man is said by a survivor to have told his family that the stream would not rise very high.

   [...]

   2The water passed over the dam about a foot above its top, beginning at about half-past 2. Whatever happened in the way of a cloud-burst took place in the night. There had been little rain up to dark. When the workmen woke in the morning the lake was full, and rising at the rate of a foot an hour. It kept on rising until 2 P. M., when it began breaking over the dam and undermining it. Men were sent three or four times during the day to warn people below of their danger. When the final break came at 3 o'clock, there was a sound like tremendous and continued peals of thunder. Trees, rocks and earth shot up into mid-air in great columns and then started down the ravine. A farmer who escaped said that the water did not come down like a wave, but jumped on his house and beat it to fragments in an instant. He was safe on the hillside, but his wife and two children were killed.

   [...]

   3Mr. Crouse, proprietor of the South Fork Fishing Club Hotel, says: "When the dam of Conemaugh lake broke the water seemed to leap, scarcely touching the ground. It bounded down the valley, crashing and roaring, carrying everything before it. For a mile its front seemed like a solid wall twenty feet high." The only warning given to Johnstown was sent from South Fork village by Freight Agent Dechert. When the great wall that held the body of water began to crumble at the top he sent a message begging the people of Johnstown for God's sake to take to the hills. He reports no serious accidents at South Fork.

   4Richard Davis ran to Prospect Hill when the water raised. As to Mr. Dechert's message, he says just such have been sent down at each flood since the lake was made. The warning so often proved useless that little attention was paid to it this time. "I cannot describe the mad rush," he said. "At first it looked like dust. That must have been the spray. I could see houses going down before it like a child's play blocks set on edge in a row. As it came nearer I could see houses totter for a moment, then rise and the next moment be crushed like egg shells, against each other."

   Table 1: The dam and the lake in numbers, compiled from T1 and T2

   Fact	Value	Where it appears
   Section of the dam rebuilt by the club	150 feet, at a cost of $17,000, from 1879 to 1881	T1, paragraph 1
   Thickness of the dam	380 feet at the base, about 35 feet at the top	T1, paragraph 1
   Usual water level	15 feet below the top of the dam	T1, paragraph 1
   Rise of the lake on May 31	about a foot an hour, from morning until 2 p.m.	T2, paragraph 2
   Water over the dam	about a foot above the top, from about 2:30 p.m.	T2, paragraph 2
   Final break	3 o'clock	T2, paragraph 2

   • Credibility of an expert inspection (T1, paragraph 1)

     When residents feared the rebuilt dam was weak, three men examined it: an engineer of the Cambria Iron Works, one "provided by Mr. Pitcairn, of the Pennsylvania Railroad," and "Nathan McDowell, chosen by the club itself." They "pronounced the structure perfectly safe."

     Result: The inspectors had expertise and were on the site, which gives their verdict weight. But all three were chosen by the companies and the club tied to the dam, so none was independent of the owners. Their verdict also dates from the rebuilding; paragraph 2 reports that by 1888 "many increasing leakages were reported." A decision in 1889 should weigh newer evidence over an old verdict.

   • Reading the numbers in two formats together (Table 1)

     T1 says the lake usually stood "15 feet below the top of the dam." T2 says the water "passed over the dam about a foot above its top."

     Result: On May 31 the lake stood about 15 + 1 = 16 feet above its usual level, far outside the conditions the inspectors had judged. Putting the two numbers side by side, as the table does, shows how unusual the day was, which the narrative does not state directly.

   • Oral testimony and the problem of repeated warnings (T1, paragraph 3; T2, paragraph 4)

     The book reports that rumors of a break were "a familiar incident of the annual freshets," and it quotes Richard Davis, who said warnings like Dechert's message "have been sent down at each flood since the lake was made."

     Result: Two independent kinds of source agree: the author's summary and a survivor's spoken account. Together they explain a decision that seems baffling afterward: people ignored the warning because earlier warnings had proved false. A warning system that sounds the same alarm for a spring freshet (a seasonal flood from rain and melting snow) and for a failing dam cannot help people decide.

   • Logging a discrepancy about the warnings (T2, paragraphs 1-3)

     Paragraph 1 says "ample time was given" by railroad officials and others. Paragraph 2 says "Men were sent three or four times during the day to warn people below." Paragraph 3 says "The only warning given to Johnstown was sent from South Fork village by Freight Agent Dechert."

     Result: Log it as partly explained: the sources may mean different warnings (general flood warnings during the day, and one urgent message that the dam was failing) and different places ("people below" the dam, and Johnstown itself). Part stays unresolved, because the page cannot say who received which warning or when. For the decision, the key point survives: warnings existed, but none was trusted.

3. Guided Practice15 minutes

   Groups of three read the early estimates of the dead that Johnson's book quotes (T3). They were made in the first days after the flood, before anyone could count. Groups compile them into Table 2, compare them on Diagram 1, and log every discrepancy. Then they make a decision: It is June 3, 1889. You are advising the relief committee, which must order food, shelter and coffins. Which figure should it plan with?

   1"This avalanche was composed of more than 100,000 tons of rocks, locomotives, freight cars, car trucks, iron, logs, trees and other material pushed forward by 16,000,000 tons of water falling 500 feet, and it was this that, sliding over the ground, mowed down the houses, mills and factories as a mowing machine does a field of grain. It swept down with a roaring, crushing sound, at the rate of a mile a minute, and hurled 10,000 people into the jaws of death in less than half an hour. And so the people called it the avalanche of death."

   [...]

   2"I cannot see how it is possible for less than five thousand lives to have been sacrificed in Johnstown alone. At least two-thirds of the town was swept away. The water came so quickly that escape from the low districts was impossible.

   [...]

   3"Here I will give the latest conservative estimate of the dead--it is between seven and eight thousand drowned and two thousand burned. The committee at Johnstown in their last bulletin placed the number of lives lost at eight thousand. In doing so they are figuring the inhabitants of their own city and the towns immediately adjoining. But it must be remembered that the tidal wave swept ten miles through a populous district before it even reached the locality over which this committee has supervision.

   [...]

   4"The Executive of the Commonwealth of Pennsylvania has refrained hitherto from making any appeal to the people for their benefactions, in order that he might receive definite and reliable information from the centres of disaster during the late floods, which have been unprecedented in the history of the State or nation. Communication by wire has been established with Johnstown to-day. The civil authorities are in control, the Adjutant General of the State coöperating with them; order has been restored and is likely to continue. Newspaper reports as to the loss of life and property have not been exaggerated.

   5"The valley of the Conemaugh, which is peculiar, has been swept from one end to the other as with the besom of destruction. It contained a population of forty thousand to fifty thousand people, living for the most part along the banks of a small river confined within narrow limits. The most conservative estimates place the loss of life at 5000 human beings, and of property at twenty-five millions.

   Table 2: Early estimates of the dead, compiled from T3

   Source (paragraph)	Who and where	Estimate	Area it covers
   Jacob Reese (1)	A Pittsburgh steel inventor describing the flood's force	10,000	not stated
   George Johnston (2)	A Pittsburgh lumber merchant who left on a train as the flood came	at least 5,000	Johnstown alone
   New York World correspondent (3)	A reporter who walked to a point across the river from Johnstown	7,000-8,000 drowned and 2,000 burned	not stated; implies more than the committee's area
   Johnstown committee (3)	The local committee's last bulletin, as the reporter relays it	8,000	the city and the towns immediately adjoining
   Governor of Pennsylvania (4-5)	An appeal for aid issued from Harrisburg, June 3, 1889	5,000 ("most conservative")	the whole valley of the Conemaugh

   Debrief. (1) Explained discrepancies: the sources cover different areas ("Johnstown alone," the committee's "own city and the towns immediately adjoining," "the valley of the Conemaugh") and different kinds of death (drowned and burned). (2) A discrepancy that exposes guessing: the Governor's figure for the whole valley, 5,000, is lower than the committee's 8,000 for a smaller area, so these figures cannot all be right; they are guesses made before any count. (3) Credibility: the Governor had the most official position, but he was appealing for donations and had waited for "definite and reliable information," yet he still vouched that newspaper reports "have not been exaggerated." (4) What happened later: the National Park Service now gives 2,209 deaths (Diagram 1), less than half of even the lowest early estimate. (5) The decision: the committee should plan for a range, not one number, and replace estimates with a register of the living and the dead as soon as possible; for food and shelter, the number of survivors matters more than the toll.

4. Independent Practice15-20 minutes

   Students now work alone on a new, invented problem. Pine Hollow Camp (an invented summer camp with 144 campers and staff) had an outbreak of a stomach illness during its first session, and it held a video call with parents before the second session. Students have three sources: the call transcript (T4, oral), the county health department's survey (Table 3, quantitative) and the camp nurse's daily log (Diagram 2, visual). They answer quiz questions 1-12 about this case, then questions 13-20 about new situations.

   1Ms. Holt (camp director): Thank you all for joining tonight's call. As you know, a dozen campers got sick during the first session. Every one of them had eaten at our July 8 cookout, so we believe the chicken was the problem, and we have already changed caterers. The lakeside fountain is safe: it passed its water test in May.

   2Dr. Lewis (county health officer): I'd like to add the results of our survey, which are in the table we sent you. Almost everyone at camp ate at the cookout, sick or not, so the cookout by itself can't tell us much. The fountain is different. Of the 46 people who drank from it, 19 became ill. Of the 98 who didn't, 5 did.

   3Mr. Tan (a parent): My daughter says she never drank from the fountain, and she was sick for two days. How does that fit?

   4Dr. Lewis: A few cases like hers are not unusual. Some campers filled water bottles at the fountain for friends, and this kind of illness can also spread from person to person in a cabin. Our follow-up questions ask about both.

   5Jo Park (camp nurse): For the record, my log shows 24 people ill: 20 campers and 4 staff members. Twelve campers went home early; the others recovered at camp.

   6Ms. Holt: And the good news is that new cases dropped right after we shut off the fountain on the morning of the 12th. That proves the problem is fixed.

   7Dr. Lewis: I'd be careful with that. This illness usually shows up one to two days after someone swallows contaminated water. The fountain is fed by a spring, and the heavy rain on the night of July 7 can wash runoff into a spring. It stays off until the spring and the pipes pass a new test.

   8Mr. Tan: So what should we expect for the second session?

   Table 3 (invented data): county health department survey of all 144 campers and staff at Pine Hollow Camp

   Group	People in group	Became ill
   Drank from the lakeside fountain, July 7-11	46	19
   Did not drink from the lakeside fountain	98	5
   Ate at the July 8 cookout	140	24
   Did not eat at the July 8 cookout	4	0

5. Closure5 minutes

   Exit ticket: "Name one discrepancy from today that has an explanation and one that you would still want resolved before a final decision. For each, say which source you would trust more and why."

   Teacher note on the historical text. The passages describe mass death plainly, including the deaths of a farmer's wife and children, and they use the overwrought style of 1889 disaster books ("the jaws of death," "the besom of destruction"). They are quoted exactly. Other chapters of Johnson's book, not used here, contain ethnic slurs about immigrant workers; if students read further, prepare them for that and discuss it as evidence of the writer's and the period's bias, which is itself a credibility question.

   Homework. Students write a decision memo on a real problem at school or in their community, using sources in three formats and a discrepancy log. Show them the directions and rubric before they leave.

Differentiation Strategies

Assessment Guidance

1. Question 1 of 20 · Multiple Choice

   Ms. Holt argues that the cookout caused the illness because every sick person ate there (paragraph 1). What does Table 3 show about this reasoning?

   AIt confirms the reasoning, because all 24 people who became ill ate at the cookout BIt disproves the cookout completely, because some people who ate there did not get sick CIt cannot test the cookout well, because 140 of the 144 people ate there, sick or healthy DIt shows the cookout was more dangerous than the fountain, because more of its eaters became ill

2. Question 2 of 20 · Multiple Choice

   Using Table 3, about how many times as high was the rate of illness among fountain drinkers as among people who did not drink from the fountain?

   AAbout 8 times as high BAbout 4 times as high CAbout half as high DAbout the same

3. Question 3 of 20 · Multiple Choice

   Ms. Holt says "a dozen campers got sick"; the nurse says 24 people were ill. What is the best way to log this discrepancy?

   AAs an error in the nurse's log, since the camp director has the official count BAs proof that the survey in Table 3 was done incorrectly CAs unresolved, since no source on the call can explain it DAs explained: 12 campers went home, while 24 people, campers and staff, were ill

4. Question 4 of 20 · Multiple Choice

   Ms. Holt says the fountain "passed its water test in May." Why does this not settle whether the fountain was safe in July?

   ABecause water tests are never accurate BBecause the May test came before the July 7 rain that can wash runoff into the spring CBecause the camp nurse, not the director, should have been the one to carry out the test DBecause the survey shows that the cookout was the real cause

5. Question 5 of 20 · Multiple Choice

   Mr. Tan's daughter got sick although she "never drank from the fountain" (paragraph 3). How should her case affect a decision about the fountain?

   AIt shows the fountain cannot be the cause, since a single counterexample disproves any pattern BIt is one of 5 cases among 98 non-drinkers, which bottles or cabin spread may explain CIt proves that the illness spread only from person to person DIt should be left out of the log, because a parent's report is not evidence

6. Question 6 of 20 · Multiple Choice

   Ms. Holt says the drop in new cases after July 12 "proves the problem is fixed" (paragraph 6). Using Diagram 2 and Dr. Lewis's comment, what is the best evaluation?

   AShe is right, because new cases fell from 9 to 5 on the very day the fountain was shut off BShe is wrong, because cases went up after the shutoff CShe is right, because there were no cases on July 15 DThe drop cannot prove it: July 12-13 cases were likely exposed before the shutoff

7. Question 7 of 20 · Multiple Choice

   Add the bars in Diagram 2. What does the total show?

   AIt is 24, matching the nurse's count of people ill, so the director's dozen measures something else BIt is 12, matching the director's count, so the nurse's log is wrong CIt is 19, matching the number of fountain drinkers who became ill DIt is 9, the largest number of new cases on any single day

8. Question 8 of 20 · Multiple Choice

   Which source is most credible on the cause of the outbreak?

   AMs. Holt, because as director she knows the camp best BMr. Tan, because his daughter was one of the people who became ill CThe county survey, because it asked all 144 people and compares groups DThe nurse's log, because it records every case on the day it began

9. Question 9 of 20 · Multiple Choice

   What should the camp do before the second session, based on all the sources?

   AKeep the fountain off until retested, provide other drinking water, and keep cabins clean to limit spread BReopen the fountain, since it passed its May test and cases have stopped CRely on the new caterer, since everyone who became ill ate at the cookout DCancel the second session, since the cause of the outbreak cannot be known

10. Question 10 of 20 · Multiple Choice

    Of the 24 people who became ill, what share had drunk from the fountain?

    AAbout 41 percent BAbout 21 percent CAbout 32 percent DAbout 79 percent

11. Question 11 of 20 · Short Answer

    Write two entries for a discrepancy log on the Pine Hollow sources. For each, cite both sources, label it (explained, error, exception or unresolved), and say how it affects the decision about the fountain.

    Show model answer

12. Question 12 of 20 · Short Answer

    Write a recommendation of four or five sentences to the camp's parents that integrates the call, Table 3 and Diagram 2. Name one discrepancy honestly and explain why your recommendation still holds.

    Show model answer

13. Question 13 of 20 · Multiple Choice

    A city council is deciding whether to add speed bumps on a residential street. It has a resident's video of cars speeding, a traffic study table of 2,000 measured speeds, and a council member's talk about "constant" speeding. What is the best way to use these sources for the decision?

    AFollow the council member, because elected officials represent residents BRely mainly on the study's measured speeds, using the video and talk as illustration CBase the decision on the video, because seeing cars speed is more convincing than a table of numbers DIgnore all three, because each source has at least one weakness

14. Question 14 of 20 · Multiple Choice

    A district report says average daily attendance was 94 percent last year. A teacher tells the school board that "a third of my students were absent on Monday." What best explains the discrepancy?

    AThe district report must be false, because a teacher saw the absences herself BThe teacher must be exaggerating, because official reports are always right CThe sources measure different things: one class on one day, and a district average over a year DBoth sources are wrong, because they cannot both be right

15. Question 15 of 20 · Multiple Choice

    When two sources on a decision disagree, which is NOT a good reason to rely more on one of them?

    AIt measured the thing directly, close to the time it happened BIt defines its terms and explains its method CIt has been checked against other records DIts speaker sounded more confident and spoke longer

16. Question 16 of 20 · Multiple Choice

    A school must choose between two bus routes. A table shows route B is 6 minutes faster on average, a driver says route B passes a construction zone that often causes delays, and a map shows route B has two more stops. Which process best meets SL.11-12.2?

    AChoose route B, because the numbers in the table are more objective than one driver's opinion BCheck when the table's times were measured and whether they include the construction CChoose route A, because the driver has the most experience DAverage the sources by giving each one vote

17. Question 17 of 20 · Short Answer

    A news report says, "The jobless rate fell from 5 percent to 4 percent, a 1 percent drop." A government table lists the same two figures. Explain the discrepancy in how the change is described, and write a sentence that describes the change accurately.

    Show model answer

18. Question 18 of 20 · Short Answer

    A chart shows that complaints about a school cafeteria fell every month for four months, and a new menu was introduced in the third month. The principal says the new menu "solved the problem." Evaluate this claim and name one additional source that would help decide.

    Show model answer

19. Question 19 of 20 · Short Answer

    A town must decide whether to repair or replace an old bridge. An engineer's inspection report from last month rates the bridge "fair," and a longtime resident tells the town meeting that "the bridge has always been fine." Evaluate the credibility of each source for this decision.

    Show model answer

20. Question 20 of 20 · Short Answer

    Describe a decision you or your family made using sources in at least two formats (for example, a review you read, a chart or price list, and a conversation). Name one discrepancy between the sources and explain how you resolved it or why you decided anyway.

    Show model answer

These standards connect to SL.11-12.2: prerequisites to review first, parallel standards at the same level, and next steps that build on it.

Standard text: Common Core State Standards for English Language Arts & Literacy. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.