ACT Preparation / Unit 20 ACT 1928 review, 2 to 3 minutes
A Research Summary
The idea
Research summaries test experimental design as much as results. A hypothesis is a testable, falsifiable explanation, and a prediction says what should happen if it is true. The independent variable is changed on purpose, the dependent variable is measured, and controlled variables are held constant, while a control group shows what happens without the treatment. Random assignment, placebos and blinding protect against confounding variables. Repeated trials make results reliable, and results can support a hypothesis but never prove it.
In practice
Worked passage, invented for the course: "Students tested whether the temperature of water affects how fast sugar dissolves. In experiment 1, they stirred 10 grams of sugar into 200 milliliters of water at 20, 40, 60 and 80 degrees Celsius, and timed how long the sugar took to dissolve: 90, 60, 40 and 25 seconds. Each time is the average of three trials. In experiment 2, they repeated the 40-degree trial without stirring, and the sugar took 180 seconds." Question one, the variables: in experiment 1, temperature is independent and dissolving time dependent; the sugar's mass, the water's volume and the stirring are controlled. Question two, what experiment 2 changed: the stirring, with temperature held at 40 degrees, so its result shows the stirring's effect, 60 seconds stirred against 180 unstirred. Question three, a prediction: at 50 degrees with stirring, the time should fall between 60 and 40 seconds, about 50. Question four, support: the hypothesis that warmer water dissolves sugar faster is supported, because the times fell steadily as the temperature rose.
Where people slip
Three habits carry forward. Name the independent, dependent and controlled variables before reading any result. Compare results only where every other condition matches. And say supports, never proves. The next unit judges explanations: models, competing viewpoints, and the evidence that decides between them.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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