VARIABLESINDEPENDENT VARIABLES

DEPENDENT VARIABLESCONTROLLED EXPERIMENTS

Analyzing Experiments

What is the Problem?

First step in the scientific method

Establishes purpose

Based on observations

Stated as a question

Why Research?

Learn more about the topic

Pick out key words in the problem question

Helps to make an educated hypothesis

Gives insight into materials that may be needed

Use internet, books, scientific magazines and articles, scientific journals, scientists/teachers, interviews, prior knowledge

What is a Hypothesis?

Is not an opinion

Is not a question. It is a statement.

Is based on research and observations

Must be testable.

It is okay if it turns out to be wrong/unsupported by data collected in experiment.

What is an Experiment?

A way to test your hypothesis

Allows you to gather data to make conclusions

Contains more than one trial

Contains variables: Controlled variables Independent (Manipulated) variables Dependant (Responding) variables

Ball Drop Experiment

Problem: Will two balls of different masses fall at the same rate?

Research: Gravity will cause any thrown or dropped ball to fall to the ground.

Hypothesis: Galileo said that objects of different masses fall at the same rate and will therefore hit the ground at the same time (ignoring air resistance).

Experiment: Drop two balls of different masses off of a table. Observe to see if they hit the ground at the same time.

What is a variable?

Anything that a scientist can change in an experiment

What are some variables in the Ball Drop Experiment? The mass of the ball The size of the ball The weight of the ball The distance it falls The height of the table Who drops the ball

What is a Independent Variable?

The one variable that is purposely changedAlso called manipulated variable

What should be the manipulated variable in the Ball Drop Experiment? The mass/type of ball

What is a Dependent Variable?

Also called the responding variableThe factor that MAY change in “response” to

the manipulated variableIt “depends” on what was changed

What is the Dependent variable in the Ball Drop Experiment? When it hit the floor/ time it takes to hit the floor

What is a Controlled Experiment?

An experiment in which only one variable is manipulated at a time.

That means only the manipulated variable changes and every other variable stays the same.

What are some variables we need to “control” in the Ball Drop Experiment? The size of the ball The distance it falls The height of the table Who drops the ball

Analyze the Results

Organize data from experiment into charts, tables, and graphs

Look for trends and/or patterns

Identify discrepancies

Supports claims in conclusions

How do I make Conclusions?

Return to your problem question and try to supply some answer. (even if the answer is: “I still do not have an answer.”)

Summarize findingsReturn to your hypothesis and compare your experiment

results to your hypothesis. Are they the same or different? Why do you think?

Make conjectures and support them with your dataExplain why your findings are important. How might they

help others?Discuss possible problems with the experiment. How could it

be improved?Discuss future experimentation that may help you answer

your questionPresent new questions your experimentation results may

have unfolded

Drawing Conclusions

Mary went downstairs. There was an aroma in the air. The table was set with warm blueberry muffins, freshly squeezed orange juice, and brewed coffee. A note was left on the table. It said, "Dear Mary, Have a great day. Good Luck at your new job. Love, Dan" Next to the note there was a wrapped present with a bow on top.

Who is Mary? A: a wife

B: a husbandC: a bakerD: a nice person

Drawing Conclusions

Mary went downstairs. There was an aroma in the air. The table was set with warm blueberry muffins, freshly squeezed orange juice, and brewed coffee. A note was left on the table. It said, "Dear Mary, Have a great day. Good Luck at your new job. Love, Dan" Next to the note there was a wrapped present with a bow on top.

What time of day is it?A: morning

B: afternoonC: evening

Drawing Conclusions

Mary went downstairs. There was an aroma in the air. The table was set with warm blueberry muffins, freshly squeezed orange juice, and brewed coffee. A note was left on the table. It said, "Dear Mary, Have a great day. Good Luck at your new job. Love, Dan" Next to the note there was a wrapped present with a bow on top.

What was the purpose of the note? A: to inform

B: to entertainC: to congratulateD: to thank

Drawing Conclusions

Mary went downstairs. There was an aroma in the air. The table was set with warm blueberry muffins, freshly squeezed orange juice, and brewed coffee. A note was left on the table. It said, "Dear Mary, Have a great day. Good Luck at your new job. Love, Dan" Next to the note there was a wrapped present with a bow on top.

Who is Dan? A: her husband

B: her bossC: her neighbor

Drawing Conclusions

Mary went downstairs. There was an aroma in the air. The table was set with warm blueberry muffins, freshly squeezed orange juice, and brewed coffee. A note was left on the table. It said, "Dear Mary, Have a great day. Good Luck at your new job. Love, Dan" Next to the note there was a wrapped present with a bow on top.

What is Mary's new job? A: store clerk

B: bakerC: real estate agentD: not enough information given

Drawing Conclusions

Mary went downstairs. There was an aroma in the air. The table was set with warm blueberry muffins, freshly squeezed orange juice, and brewed coffee. A note was left on the table. It said, "Dear Mary, Have a great day. Good Luck at your new job. Love, Dan" Next to the note there was a wrapped present with a bow on top.

Who probably made the muffins, orange juice, and, coffee?

A: MaryB: Dan

Drawing Conclusions

Mary went downstairs. There was an aroma in the air. The table was set with warm blueberry muffins, freshly squeezed orange juice, and brewed coffee. A note was left on the table. It said, "Dear Mary, Have a great day. Good Luck at your new job. Love, Dan" Next to the note there was a wrapped present with a bow on top.

Why was there a present on the table? A: to congratulate

B: a thank you giftC: to say sorryD: not enough information given

Drawing Conclusions

Miss Amole is always trying to save money, but she also likes a quality product. She decided to do an experiment to see if the “cheap” paper towels were just as strong as the “expensive” ones. She bought two types of paper towels: Brawny (expensive) and Bounty (cheap). Miss Amole thought the Brawny paper towels would be stronger since they were more expensive. She placed both paper towels in a bowel that contained the same amount of water. After soaking for one minute, Miss Amole rung both paper towels out as best she could and unwrinkled them. She then placed a soup can on the paper towels and observed how long the paper towels could hold the can before tearing. The Bounty held for 20 seconds and the Brawny held for 5 seconds.

What conclusions can we make?

Drawing Conclusions

The graph below shows the relationship between maternal age and the incidence of children born with Down syndrome (a condition that results in an individual having an extra chromosome 21).

What conclusion is best supported by the data?

A. There is no risk of Down syndrome in children born to mothers under age 34.

B. The risk of Down syndrome increases dramatically in children born to mothers after age 34.

C. The risk of Down syndrome doubles in children born to mothers for each year over the age of 34.

D. There is no correlation between the number of Down syndrome births and age.

Drawing Conclusions

Environmental monitoring of a lake located to the southeast of a factory has shown a consistent decrease in pH over the period of a year. A researcher investigating the pH change hypothesizes that either a factory or

a farm along the river is responsible for the pH change. The river flows into the lake.

The researcher collects a water sample from locations Y and Z in the diagram and runs pH analyses on each sample. He finds that the pH in sample Z is lower than the pH in sample Y and concludes that the factory is responsible for the low pH values in the lake.

Based on the diagram and the researcher’s investigation, provide two reasons why this may not be a valid conclusion. Describe how each reason could invalidate the conclusion.