Scientific Method
What is the first step scientists usually take when beginning an investigation?
Ask a questions/ identify a problem
What is the variable that the scientist purposely changes?
Independent variable
Name one liquid we tested on our pennies.
Ketchup, Coke, vinegar, salt water, lemon juice or water
What tool could you use to measure how much liquid you put into a cup?
Measuring cup, graduated cylinder, etc.
You want to find out which paper towel absorbs the most water. What could you change?
The brand/type of paper towel
What is a testable question?
A question that can be investigated or tested through an experiment.
What is the variable that you measure or observe?
Dependent variable
What was the independent variable in our penny experiment?
Why should scientists record their observations and data?
So they have evidence they can analyze and use to draw a conclusion
You test three brands of batteries. What should you keep the same to make it a fair test?
Things such as the amount of water, the size of the battery-powered device, testing conditions, etc.
What is a hypothesis?
A prediction or educated guess about what will happen.
What are constants?
Factors that are kept the same throughout an investigation
In our penny experiment, we tested ketchup, Coke, vinegar, salt water, and water. What was the independent variable?
The type of liquid used to clean the penny.
Why is it important to repeat an investigation or have multiple trials?
Repeating trials makes results more reliable and helps reduce the effect of unusual results
A student thinks plants grow faster with more sunlight. What would they measure to determine if their hypothesis is supported?
Plant growth/height
What should you do after collecting your data?
Analyze the data and/or draw a conclusion
In an investigation, you change the amount of sunlight a plant receives and measure how tall it grows. What is the independent variable?
Amount of sunlight
We left every penny in its liquid for one week. What type of variable was the one-week soaking time?
A constant.
What is the difference between an observation and an inference?
An observation is something you notice or measure; an inference is an explanation or conclusion based on observations
A student tests Coke on one penny and ketchup on five pennies. Is this a fair comparison? Why or why not?
No. The number of pennies should be the same for each liquid so the test is fair.
What is the purpose of a conclusion?
To explain what the data shows and whether the evidence supports the hypothesis
A student tests whether different amounts of water affect plant growth. Name the independent variable, dependent variable, and one constant.
Suppose your group predicted that Coke would clean the penny best, but vinegar actually produced the cleanest penny. What should you say in your conclusion?
The results did not support our hypothesis. Vinegar cleaned the penny better than Coke under the conditions of our experiment.
Why is it important to change only one variable at a time?
Changing multiple variables makes it difficult to know which variable caused the result.
You get results that do not support your hypothesis. Does that mean the investigation failed? Explain.
No. A hypothesis is a prediction. Scientists use evidence to determine whether the evidence supports or does not support the hypothesis.