A comprehensive lesson that teaches students how to use the Claim-Evidence-Reasoning (CER) framework to analyze pivotal moments of 19th-century US expansion: the Texas Revolution, the Mexican-American War, and the California Gold Rush. It includes a step-by-step instructional slide deck, highly scaffolded station activities with primary and secondary sources, a practice worksheet, and a teacher facilitation guide with rubrics and keys.
Helpful Background: The clash happened in the "Nueces Strip"—a piece of land between two rivers that both countries claimed as theirs. President Polk sent US soldiers directly into this disputed area, which caused the Mexican army to shoot.
YOUR 3-STEP CER WRITING PLAN
STEP 1: THE CLAIM (C) — Fill in the blank to make your answer
Starter Frame: "The United States' declaration of war against Mexico was [justified / unjustified] because..."
The US declaration of war against Mexico was ________________________________ because __________________________________________________.
STEP 2: THE EVIDENCE (E) — Use clues from the document above
Starter Frame: "President Polk claimed that '...' but the background note says that..."
The text states that "_____________________________________________________________________________________________."
STEP 3: THE REASONING (R) — Complete the logical sentence puzzle
This evidence is critical because even though the President said Mexico started the fight, the US army was actually sent into .
As a result, this proves my claim because it shows that the US was deliberately trying to instead of waiting for a peaceful agreement.
WESTWARD DETECTIVES
NAME:
DATE:
STATION 3
The California Gold Rush (1848–1855)
CLUE FOCUS: HUMAN IMPACT
THE BIG MYSTERY:
How did the discovery of gold at Sutter’s Mill affect the Native American tribes living in California?
Document C: Native California History Records HISTORICAL REPORT
"Before gold was found, California had over 150,000 Native Americans. By 1870, less than 30,000 were still alive. Over 300,000 new miners arrived. They destroyed Native hunting grounds, ruined the river water with chemicals, and forced tribes off their land. The California government even spent $1 million paying armed militia groups to force Native tribes away."
Helpful Background: The United States took over California in 1848 right before gold was found. US laws did not give Native Americans, Chinese immigrants, or Mexican miners any basic human rights.
YOUR 3-STEP CER WRITING PLAN
STEP 1: THE CLAIM (C) — Fill in the blank to make your answer
Starter Frame: "The discovery of gold in California had a devastating impact on Native Americans by..."
The discovery of gold in California had a devastating impact on Native Americans by ___________________________________________.
STEP 2: THE EVIDENCE (E) — Use clues from the document above
Starter Frame: "Document C explicitly states that the Native American population dropped from..."
Document C states that the Native population dropped from ________________ to ________________ because miners ______________________.
STEP 3: THE REASONING (R) — Complete the logical sentence puzzle
This evidence shows that the rapid growth of the gold mining industry came at a massive cost because .
This proves my claim because it shows that the Gold Rush was not just about getting rich, but was actually a system that destroyed the of the people who were already living in California.
Helpful Background: John O'Sullivan coined the term "Manifest Destiny" to justify taking land. At this time, millions of acres of land were taken through war, treaties, and forcing Native Americans off their homelands.
CONSTRUCTING YOUR CER ARGUMENT
1. THE CLAIM (C) — Fill in the blank side you pick
The idea of Manifest Destiny was __________________________________________ because it was focused on ___________________________________________.
2. THE EVIDENCE (E) — Write a direct quote or detail from the source above
In the text, John O’Sullivan states that "___________________________________________________________________________________________________________."
3. THE REASONING (R) — Solve the logical sentence puzzle
This evidence is important because it shows that , which means that the United States wanted to .
Therefore, this proves my claim because the expansion was motivated by .
GRADE 6 // SYNTHESIS EXIT SHEET PAGE 2 OF 2
Claim (C)
Answers the question directly. No personal pronouns. Bold and clear.
Answers the question, but is slightly vague or uses personal language ("I think").
Incomplete or missing claim; does not answer the actual query.
Evidence (E)
Includes a direct quote or highly specific fact from the document.
Points to the source generally, but lacks a precise quote or clear detail.
No evidence is used, or the information is made up and not in the text.
Reasoning (R)
Correctly uses sentence puzzles to explain how the evidence proves the claim.
Attempts to link the claim and evidence, but just repeats the quote in a simpler way.
No logical reasoning is provided; student just says "this proves it."
6th Grade Station Exemplars (For Easy Grading)
STATION 1: TEXAS
Claim: ...rebelled against Mexico because they wanted to keep using slave labor to grow cotton. Evidence: Document A says "Texas must be a slave country... what we have been working for." Reasoning: Settlers cared most about making money from farming. They started the war to protect slavery instead of obeying Mexico.
STATION 2: MEXICAN WAR
Claim: ...was unjustified because the US sent soldiers onto Mexican land to provoke them. Evidence: The text states the US sent soldiers directly into the disputed "Nueces Strip." Reasoning: Sending armed troops onto disputed land means the US was trying to trigger a border war to grab land.
STATION 3: CALIFORNIA
Claim: ...had a devastating impact on Native Americans by destroying their homes and lives. Evidence: Document C says the Native population fell from 150,000 to under 30,000. Reasoning: This massive drop shows rapid development came at a huge human cost, destroying their families.
