THE VOCABULARY DETECTIVE
The lamp that got all the credit
Listening is optional. It can help you follow the story and hear how the words are pronounced. You can solve the case using the book alone.
Listen to the case
Download storyHear each word
Listen at normal speed, or slow it down to hear each sound.
variable
isolate
correlation
causal
Choose Normal or Slow to listen.
Read along with the story
“Look how tall these are!” The garden club wanted a new lamp after seeing its trial plants. Those plants had grown more than the ones by the window. Was the lamp the reason?
Their teacher asked about each variable—something that could differ between the groups, such as water or starting height. To isolate the lamp’s effect, they needed to keep the other conditions alike. Changing several things at once would make the result harder to explain.
The notebook showed a correlation: plants under the lamp had grown more. A causal claim went further. It said the lamp had produced that extra growth.
Before spending the club’s money, Nina opened the growing log. She would compare what each group received, not just how tall the plants were at the end.