What is the purpose of a control group in an experiment?

To provide a baseline with no treatment to compare the experimental groups against

Why should an experiment change only one variable at a time?

So that any change in the dependent variable can be attributed to that one independent variable

Both rise with hot, sunny weather, so this is a correlation, not causation

It is not to scale and does not show the real chemical bonds or dynamic copying

A broad, well-supported explanation backed by a large body of evidence

Because science is self-correcting and updates explanations when strong new evidence appears

12questions. Pick an answer and you'll see why right away.

In an experiment testing how fertilizer amount affects plant height, what is the dependent variable?
What is the purpose of a control group in an experiment?
Why should an experiment change only one variable at a time?
A student records the mass of a seedling once a day for two weeks. Which graph best displays the data?
On a graph, where should the independent variable be plotted?
Three trials give oxygen volumes of 18 mL, 22 mL, and 20 mL. What is the mean volume?
A reaction produces 30 mL of gas in 3 minutes. What is the mean rate?
What are the three parts of a complete scientific conclusion?
Towns with more ice cream sales also report more sunburn. What is the most valid conclusion?
Which statement best describes a limitation of a bead-and-pipe-cleaner model of DNA?
What does a scientific theory mean?
Why is it a strength that scientific knowledge can be revised?