Scientific Method & Lab Safety Review

Carmen conducted an experiment to determine if listening to different types of music would affect a person’s pulse. Her hypothesis was that pulse rate would change with different types of music. Each person listened to seven different selections of music for 30 seconds each. Each person’s pulse was taken before the music and then after each 30-second interval of music. The pulses were taken again after the music selections were completed. Based on her experiment, Carmen concluded that a person’s pulse rate changed when the person listened to different types of music.  Which component is missing from Carmen’s experiment?

• a question
• a hypothesis
• a control group
• a description of the experiment

In an appropriately designed experiment, a scientist is able to test the effect of

•  a single variable
•  multiple variables
•  the hypothesis
•  scientific observations

Which statement best expresses a basic scientific assumption?

• Interpretation of experimental results has provided explanations for all natural phenomena.
• If a conclusion is valid, similar investigations by other scientists should result in the same conclusion.
• For any conclusion to be valid, the design of the experiment requires that only two groups be compared.
• After a scientist formulates a conclusion based on an experiment, no further investigation is necessary.

Conclusions based on an experiment are most likely to be accepted when

• they are consistent with experimental data and observations
•  they are derived from investigations having many experimental variables
•  scientists agree that only one hypothesis has been tested
•  hypotheses are based on one experimental design

An experiment was carried out to determine whether drinking caffeinated soda increases pulse rate. The pulse rates of two groups of people at rest were measured. Group A was then given caffeinated soda and group B was given caffeine-free soda. One hour after drinking the soda, the pulse rates were measured. The participants in the experiment were all the same age, and they were all given the same amount of soda. The dependent variable in this experiment is the

• type of soda given to each group
• amount of soda given to each group
•  pulse rate of each group
• age of participants in each group

What is a hypothesis?

• the thing changed on purpose in the experiment

• an explanation about what you observed

• using your 5 senses to gather data

• an educated guess about the outcome of an experiment

What two words should be in your hypothesis?

• I think

• If ...then...

• It will

• No idea

What variable comes after the word IF

• independent variable

• dependent variable

What variable comes after the word then?

• independent variable

• dependent variable

When is a hypothesis written?

• before you decide on a question

• after the experiment

• before the experiment

• after the conclusion