Worked examples
Two examples
Example 1
Kenji wants to know whether a fan helps wet laundry dry faster. He soaks six towels of the same size in the same amount of water. He hangs three towels in front of a fan and three towels in the same room with no fan. He checks every 15 minutes and writes down how long each towel takes to dry.
- The independent variable is the one thing changed on purpose. Kenji changes one thing: whether a towel hangs in front of the fan.
- The dependent variable is what is measured to see the effect. Kenji measures how long each towel takes to dry.
- One way to keep them apart: the independent variable is what you do; the dependent variable is what you watch.
Answer: Independent: fan or no fan. Dependent: the time each towel takes to dry.
Example 2
Kenji wants to know whether a fan helps wet laundry dry faster. He soaks six towels of the same size in the same amount of water. He hangs three towels in front of a fan and three towels in the same room with no fan. He checks every 15 minutes and writes down how long each towel takes to dry.
- Was the size changed on purpose? No: every towel is the same size.
- Was it measured to see the effect? No: Kenji measures drying time, not size.
- It was kept the same for every part of the test, so that only the fan differs. That makes it a controlled variable. The amount of water and the room are controlled variables too.
Answer: A controlled variable
Where this is taught: Science Practices, part 3: The scientific method and a fair test · Look Again Quiz 2: The Scientific Method · Change One Thing, the scientific method app
In your Kaplan book: Unit 4, Chapter 1, Lesson 2: Use the Scientific Method · Map of the Terrain, topic 2: The scientific method
The drill
Ten questions
Read what is in the box first, if there is one. Then tap your answer; a few questions ask you to choose words from a drop-down instead, the way the GED test does. Press Check my answers at the bottom.Read what is in the box first, if there is one. Circle your answer; where there are brackets, circle the choice that fits. The answer key, with the reasoning, is on the last page.