Scientific Investigation

What is data?

Data are recorded observations collected during an investigation. Scientists analyze data to identify patterns and draw conclusions.

What is qualitative data?

 Data based on observations using the senses and described with words rather than numbers.

What is quantitative data?

Data based on measurements represented by numbers, usually collected using instruments.

What is a hypothesis?

A testable prediction or explanation that can be tested through additional observations or experiments.

How are hypotheses commonly written?

They are often written as “If…, then…, because…” statements.

What can happen to a hypothesis after an experiment?

The results can support or refute the hypothesis.

What is a null hypothesis?

A hypothesis stating that there is no statistically significant difference between groups and that any observed difference is due to chance.

What does a researcher try to do with the null hypothesis?

They try to reject the null hypothesis using evidence from their data.

What is an alternative hypothesis?

A hypothesis stating that there is a difference or effect between groups.

What is an independent variable?

The one factor intentionally changed by the researcher in an experiment.

What is a dependent variable?

The factor that is measured or observed to determine the effect of the independent variable.

What is a control group?

The group that provides a baseline for comparison so researchers can determine whether the independent variable caused a change.

Why are control groups important?

They help reduce experimental errors and researcher bias and make it easier to determine whether the independent variable caused the observed effect.

Is the control group always the group that receives nothing?

No. The control is the baseline condition being compared to the experimental treatment. It can sometimes receive a standard treatment.

What is a constant?

A factor that does not change throughout the experiment and is kept the same for all groups.

What is the difference between a variable and a constant?

A variable changes during an experiment, while a constant stays the same.

What should a well-designed experiment include?

An independent variable, dependent variable, control group, constants, and 3–15 trials.

Why are multiple trials important?

Repeating an experiment helps make the results more reliable and reduces the effect of random error.

What is a scientific theory?

A well-supported explanation of natural phenomena that summarizes a large body of evidence. Theories can generate new hypotheses and are generally widely accepted.

Can a scientific theory become a scientific law?

No

What is a scientific law?

A statement of fact describing a consistent pattern or observation in nature, often expressed as a mathematical formula.

Does a scientific law explain why something happens?

No

Can a hypothesis be proven true?

No

What is the main difference between a scientific theory and a scientific law?

A theory explains how or why something happens, while a law describes what happens. Neither is simply a “higher level” of the other.