The big idea
⚖️
An experiment is a fair comparison
Built so that only one thing differs. Everything else is bookkeeping.
Scientific Thinking · Lesson 5
Variables and Experimental Design
beginner⏱ 18 min · 7 cards
Try it
Design the Test
“Amount of fertiliser applied”
In a study of fertiliser on plant growth, which role does each play?
Assign each factor its role in the study.
The safeguards
Four defences
Tap each.
Key term
The question that exposes weak evidence
"Patients improved after treatment." So?
tap to reveal ↻
Compared to what?
Many conditions improve anyway, and people seek treatment when symptoms peak. Without a control group there is no finding — only a story.
Nuance
HMS Salisbury, 1747
Think like a Maester
Lind held diet and quarters constant and ran six treatments against each other at once. Good design identified citrus long before anyone knew vitamin C existed.
Quick check
What single question best tests whether a claim is scientific?
You did it
Nice work
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