Grade 8 · Evaluating Sources and Reasoning · Source Quality and Faulty Reasoning
Evaluating Evidence and Spotting Faulty Reasoning
Test a source for authority, currency and purpose, and name four common reasoning errors.
Learning objectives
- Apply four source tests to a real website
- Distinguish correlation from causation
- Name and identify four reasoning errors
Common Core ELA alignment
RI.8.8
Trace and evaluate the argument and specific claims in a text, distinguishing claims that are supported by reasons and relevant evidence from claims that are not. Grade 8 emphasis: analyse subtler techniques such as irony, conflicting evidence and differing interpretations.
RI.8.6
Determine an author's point of view or purpose in a text and explain how it is conveyed and how it distinguishes their position from others. Grade 8 emphasis: analyse subtler techniques such as irony, conflicting evidence and differing interpretations.
RI.8.1
Cite textual evidence to support analysis of what an informational text says explicitly as well as inferences drawn from the text. Grade 8 emphasis: analyse subtler techniques such as irony, conflicting evidence and differing interpretations.
MYP criteria
- Criterion A — Analysing
- Criterion D — Using language
ENGAGE
Ice cream and drowning
Ice cream sales and drowning deaths rise together every summer. Nobody sensible concludes that ice cream causes drowning. Something else, hot weather, causes both.
Think about it
- What is the hidden third factor?
- Where have you seen this mistake made seriously?
EXPLAIN
Two toolkits
Toolkit 1: four source tests
| Test | Question |
|---|---|
| Authority | Who wrote it and what qualifies them? |
| Currency | When was it published or last updated? |
| Purpose | Is it selling, persuading, informing or entertaining? |
| Corroboration | Does an independent source agree? |
Toolkit 2: four reasoning errors
| Error | What it looks like |
|---|---|
| Correlation as causation | Two things rise together, so one caused the other. |
| Hasty generalisation | One or two cases treated as a rule. |
| False dilemma | Only two options offered when more exist. |
| Appeal to popularity | Everyone thinks so, therefore it is true. |
Careful
A biased purpose does not automatically make a source wrong. It tells you to check the evidence harder, not to dismiss it.
EXPLORE
Judge three claims
- Students who own laptops score higher, so buying a laptop raises grades.
- My cousin school banned phones and results improved, so bans work everywhere.
- Either we ban phones or we accept failing results.
Think about it
- Name the reasoning error in each claim.
- What evidence would you need to rescue claim 1?
MYP_PRACTICE
Criterion D task
Pick a website making a health or education claim. Complete the four source tests in a table, then write 120 words judging whether you would cite it in an essay and why.
EXIT_TICKET
Check yourself
Think about it
- Explain correlation versus causation in one sentence.
- Which source test do you usually skip?
Interactive practice · source check
Run the four tests
Enter a real source and record authority, currency, purpose and corroboration, then give a verdict.
Record your findings
Your answer
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Key vocabulary
- Authority
- Whether the author has relevant expertise.
- Corroboration
- Independent confirmation from another source.
- Correlation
- Two things changing together without proof one causes the other.
- False dilemma
- Presenting only two options when others exist.
Practice questions
0/2 correct
Level 1 · Criterion D
My cousin school banned phones and results improved, so bans work everywhere is which error?
Level 2 · Criterion D
Which source test asks whether the text is trying to sell you something?
MYP criterion tasks
Level 3 · Criterion A
Explain what evidence would be needed to support the laptop claim properly.
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