Scientific Process
What is the first thing a scientist should do when beginning an investigation?
Ask a question / identify the problem.
What is a variable?
Something that can change in an experiment.
A student changes the amount of water given to plants to see how it affects their growth.
What is the independent variable?
Amount of water
A student changes the amount of water given to plants and measures their height.
What is the dependent variable?
Plant height/growth
Marcus wants to see whether sunlight affects plant growth.
He changes the amount of sunlight and measures plant height.
What should he keep the same?
Examples: type of plant, amount of water, soil, pot size, etc.
What is a hypothesis?
An educated, testable prediction.
Which variable does the scientist change on purpose?
Independent variable
A student tests whether different amounts of sunlight affect plant growth.
What is the independent variable?
Amount of sunlight
A scientist changes the water temperature and records how long it takes sugar to dissolve.
What is the dependent variable?
Time it takes the sugar to dissolve
A scientist changes the amount of water given to plants and measures their growth.
Identify:
Independent variable: ?
Dependent variable: ?
Independent = Amount of water
Dependent = Plant growth/height
After scientists collect data during an experiment, what should they do with it?
A. Share it
B. Analyze it
C. Change it
D. Throw it away
B. Analyze it
Which variable is measured or observed?
Dependent variable
A scientist changes the temperature of water to see how quickly sugar dissolves.
What is the independent variable?
Water temperature
A student changes how many hours she studies and records her test scores.
What is the dependent variable?
Test scores
A student tests whether water temperature affects how quickly an ice cube melts.
What should be kept the same?
Examples: size/type of ice cube, amount of water, container, etc.
Why is it important for scientists to record their observations and data?
So they can analyze the results and use evidence to draw conclusions.
What are controlled variables/constants?
Things that are kept the same during an experiment.
A student tests three different brands of paper towels to determine which absorbs the most water.
What is the independent variable?
Brand/type of paper towel
A student tests different paper towel brands and measures how much water each towel absorbs.
What is the dependent variable?
Amount of water absorbed
A student wants to know whether studying longer improves quiz scores.
She has students study for different amounts of time and then gives everyone the same quiz.
Identify the:
Independent variable
Dependent variable
Independent = Amount of study time
Dependent = Quiz score
Put these steps in a logical order:
Draw a conclusion → Ask a question → Conduct the experiment → Form a hypothesis
Ask a question → Form a hypothesis → Conduct the experiment → Draw a conclusion
Complete the sentence:
The independent variable is what I ______, and the dependent variable is what I ______.
Change; measure/observe
A student gives four plants 0 mL, 10 mL, 20 mL, and 30 mL of fertilizer each week and measures their heights.
What is the independent variable?
Amount of fertilizer
Students change the amount of exercise they do each day and record their heart rates immediately afterward.
What is the dependent variable?
Heart rate
A scientist wants to know whether fertilizer affects plant growth. She uses the same type of plant, soil, pot, sunlight, and water but gives each plant a different amount of fertilizer.
Identify all three:
Independent variable
Dependent variable
One controlled variable
Independent = Amount of fertilizer
Dependent = Plant growth/height
Controlled = Type of plant, soil, pot, sunlight, or water