Arthur is studying plants, and he wants to learn more about why tree leaves change colors in the fall. His teacher suggested that he do a scientific experiment, starting with making a testable hypothesis. Which of the choices below is a possible hypothesis for Arthur to investigate?

Question

A.
If I stop watering the trees in my yard early in the summertime, their leaves will change color before the neighbors' trees change.
B.
Why do some leaves change colors, and others don't?
C.
If I water the trees in my yard all winter, will they stay green until spring?
D.
My house has more trees around it than any other house on our street.

Answer 1

The best option for a testable hypothesis that Arthur can investigate is:

A. If I stop watering the trees in my yard early in the summertime, their leaves will change color before the neighbors' trees change.

This hypothesis is testable because it proposes a clear cause-and-effect relationship that can be observed and measured: the effect of watering (or lack thereof) on the timing of leaf color change compared to neighboring trees. The other options are either questions (B, D) or do not provide a clear testable hypothesis (C).