SWBAT: Describe how to conduct a controlled experiment
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SWBAT: Describe how to conduct a controlled experiment Methodology Question(Problem) Hypothesis ( If-Then statement ) Research Design experiment Conduct Experiment & Collect Data

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SWBAT: Describe how to conduct a controlled experiment

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SWBAT: Describe how to conduct a controlled experiment


Question(Problem) Hypothesis (If-Then statement)

Research Design experiment

Conduct Experiment & Collect Data

Display & Analze Data Draw Conclusion

Presentation (Oral)

Teacher Conferencing the Question

  • What is your question?

  • Why have you chosen this question?

  • What do you already know about this problem or issue?

Example: Mary suggested that she wanted to do an exit project on

How do Sunflowers grow?

Why? Because she likes to eat them all the time.

What do you know about sunflowers? Mary stated that all she knows is that they grow tall?

Is this good enough for an exit project ? Why or why not?

What do you know about sunflowers or plants in general?

Can we turn any of what you know into a “testable” question?

Background Research

  • Sunflowers grew wild all over North America http://www.historyforkids.org/learn/food/sunflowers.htm

  • Planting corn with sunflowers as companions drives away Carpophilus Beetles http://www.rain.org/~philfear/sunflowerhouse.html

  • Plant in full sun after the last frost; plant seeds one inch deep; thin to 1 ½ inches apart; water well and keep moist; sunflowers are harvested for their seeds http://www.seedsofknowledge.com/sunflowers.html

Continue to Modify the Question

What type of soil will allow the sunflower plant to grow the best?

  • What do you mean by “soil”? What type of soil?

  • What do you mean by “the best”?

  • What types of soil are you thinking of?

Final Question:

  • What type of soil media will allow the sunflower plant to grow the tallest: perlite, vermicompost or a mixture of both?

Can we now turn our testable question into a hypothesis?

(Using the If…. Then ……. Because format)

Creating Your Hypothesis

  • A hypothesis is an educated guess based on prior knowledge and background research.

  • One way to set up a hypothesis is the use the “if…….then……..because……..” formula.

Formulating the Hypothesis

  • If sunflower seeds are planted in a 50%-50% mixture of perlite and vermicompost then they will grow the tallest.

  • Based on my background research, the plants will receive nutrients from the vermicompost and sufficient aeration and support from the perlite.

Determine the Variables within your Question

  • There are 3 types of variables defined in a controlled experiment

    • independent variable

    • dependent variable

    • controlled variables (constants)

Define “Variables”

  • Variable: Something that can vary or change. Can be manipulated by the scientist.

    • Independent Variable:

      • the variable that is manipulated or changed by the scientist.

      • this variable is manipulated at the onset of the experiment.

    • Dependent Variable:

      • is a result of the independent variable

      • this variable is measured throughout or at the end of the experiment

    • Controlled Variables (Constants):

      • these variables remain constant (the same) for each level

      • they are controlled by the scientist

Determining Variables within the Question

  • Question:What type of soil media will allow the sunflower plant to grow the tallest?

  • What is the independent variable?

    • type of soil media

  • What is the dependent variable?

    • height of the sunflower

  • What are the controlled variables (constants)?

    • container size

    • amount of medium

    • temperature

    • water

    • sunlight

Setting Up your Experiment

  • Materials Use or Needed

  • 15 3” pots of equal size

  • perlite

  • vermicompost

  • measuring cup

  • water

  • Grow Lab

  • ruler

  • pencil

  • Science journal

Setting Up the Experiment

  • Procedure: Clearly describe how you will set up your experiment. Include:

    • Introduction

    • independent variable

    • dependent variable

    • all necessary constants

    • at least 5 different levels of the independent variable

    • repeated trials

    • sufficient data gathering to support or not support your hypothesis

Procedure includes 5 Levels of Independent Variable

Repeated Trials:

Sufficient Data Gathering to Support or Not Support My Hypothesis:

I will observe the growth of my plants and take measurements ever day.

Communicate Results

  • Step #5 in the Scientific Method is to communicate your results to other scientists (and the public).

Communicating Results

  • Gather Data

    • Record in Journal

    • Record in a Table

  • Transpose Data

    • Record on a Graph

  • Write a Statement of Relationship

  • Write a Conclusion

  • Determine Possible Errors

  • Decide on Ideas for Further Study

Record Raw Data in a Table

Table:Measuring Growth of Sunflower Plants in 100% Perlite (cm)

Next Step…

  • What do you do with your Raw Data?

Transpose Raw Data Into a Graph

  • What kinds of graphs are there?

    • Line Graph: line accounts for all data collected

    • Bar Graph: bars are accurately drawn

  • What kind of graph does our question require?

Review our question to determine what kind of graph best relates:

  • What type of soil media will allow the sunflower plant to grow the tallest: perlite, vermicompost or a mixture of both?

Bar Graph

Requirements of a Graph:

  • Graph: Bar or Line

    • include a descriptive title

    • axes are labeled

    • numbers on the axes are recorded beginning from the corner of the graph

    • equal intervals are used

Bar Graph

Line Graph

Statement of Relationship

  • accurately describes the relationship between the independent and dependent variable

  • describes all changes in relationships and tells when they occur (line graph)

  • the statement is read directly from the graph


  • Have a conversation with your students about their experiment.

    • How are they interpreting the data?

    • What conclusions have they drawn?

    • What have they learned from the experiment?

    • Based on their experiment where does their curiosity take them next?

    • What went wrong?

    • What are they proud of?


  • Attempts to explain why the results happened as they did

  • Compares findings to the hypothesis by stating whether data supported or did not support the hypothesis

  • States limitations and possible errors

  • Include possible future investigations

For Further Investigation

Possible Errors/Limitations

For Further Investigation

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