Students will learn and implement experimental design vocabulary while practicing their critical thinking skills in an inquiry-based experiment. This lesson is written using the 5E learning model, which includes five phases: engage, explore, explain, elaborate, and evaluate.

Learning outcomes

  • Students will define and apply the experimental design vocabulary.
  • Students will use the experimental design graphic organizer to plan an investigation.
  • Students will design and complete their own scientific experiment.

Teacher planning

Time required

Approximately 6 class periods (50 minutes each) are needed, however, some things can be assigned as homework to decrease the time spent in class.

Materials needed

  • supplies for the experiment: Dixie drinking cups, Pepsi and Coke (1.5 to 2 ounces per student), and optionally ice to keep soda cold
  • overhead projector

Student handouts

Experimental design graphic organizer
One copy for each student and one copy as an overhead transparency.
Open as PDF (114 KB, 2 pages; also available as Microsoft Word document)
Experimental design vocabulary organizer
Open as PDF (13 KB, 1 page; also available as Microsoft Word document)
Experimental design: Explore worksheet
Open as PDF (37 KB, 1 page; also available as Microsoft Word document)
Experimental design: Explain worksheet
Open as PDF (5 KB, 1 page; also available as Microsoft Word document)
Experimental design vocabulary definitions
Note: Alternatively, dictionaries may be used.
Open as PDF (36 KB, 1 page; also available as Microsoft Word document)

Activities

Engage

What are the “rules” for designing an experiment?

The teacher and class will discuss the following questions:

  • Is there a specific way to design an experiment?
    Try to lead students to mention the scientific method and discuss any “holes” in this approach.
  • Are their rules scientists follow when designing an experiment?
  • Are all experiments designed in the same way?
  • What kinds of experiments have you done on your own?
    Good things to discuss are cooking, testing sports techniques, trying to fix things, etc. Try to relate experimentation to their everyday life.

Explore

Review an experiment and answer questions.

Using the Explore worksheet, students will read a description of an experiment and answer questions about the design of the experiment without using the vocabulary.

Explain

Vocabulary introduction and application

  1. Students will define the experimental design vocabulary using the vocabulary organizer. Students will need three copies of this organizer. The vocabulary terms they should define include independent variable, dependent variable, control, constant, hypothesis, qualitative observation, quantitative observation, and inference. Definitions are available in the Critical Vocabulary section of this lesson and in the vocabulary definitions listed in the Supplemental Information section of this lesson.
  2. Students will review the Explore worksheet and match the vocabulary to the pieces of the experiment. Review answers with the class.
  3. Students will read a second experiment description in the Explain worksheet and identify the pieces of the experiment using their vocabulary definitions.

Elaborate

Introduce experimental design graphic organizer and complete class-designed experiment.

  1. Before beginning this lesson, the teacher should preview the:
    Pepsi-Coke experimental design graphic organizer example
    Open as PDF (114 KB, 2 pages; also available as Microsoft Word document)
  2. Use the overhead projector to display the blank experimental design graphic organizer and complete as a class.
  3. Tell the class that you are going to do the Pepsi-Coke Challenge. The question they need to answer is: Can girls taste the difference between Pepsi and Coke better than boys?
  4. As a class, plan the Pepsi versus Coke experiment. This is a good time to discuss double-blind studies and why it is important to make this a double-blind study. Students can look at the results within their own class as well as the whole team.
  5. This is also a good chance to test multiple variables. You do not need to let students know this, but if the data chart also records things like age, frequency of drinking soda (daily, weekly, monthly, rarely), ability to roll tongue, or anything else they think might be interested in, the results can be analyzed for each variable.
  6. Using the Pepsi-Coke data calculations and the Pepsi-Coke data table (linked below), complete the experiment and analyze data. Students should make a bar graph of their results listing each variable with the percent correct. As a class you should discuss the reliability of the results. Does gender actually affect your ability to taste?
    Pepsi-Coke data calculations
    Open as PDF (68 KB, 2 pages; also available as Microsoft Word document)
    Pepsi-Coke data table
    Open as PDF (116 KB, 1 page; also available as Microsoft Word document)

    Hints

    • I removed the labels from the bottles and labeled them A and B. I used a different labeling system under the cups so the students did not see a pattern (numbered cups were Pepsi, lettered cups were Coke).
    • I recorded the data and organized the tasting while students completed other work in their seats. Two students at a time tasted the soda and I recorded data. You could also have a volunteer who is not participating help with this.
    • Check for students who do not want to drink soda as well as any dietary needs such as diet soda.
    • Do not verify guesses until all of the students have completed the experiment.

Evaluate

How can you accurately remember the pieces of an experiment?

For assessment purposes, students should choose one of the following assignments or some other teacher-approved assignment.

  • Write a poem about four of the vocabulary words.
  • Write a song about four of the vocabulary words.
  • Create a memorization tool for four of the vocabulary words.
  • Make a poster about four of the vocabulary words.

Teachers should evaluate the finished assignments to ensure they show an understanding of the vocabulary.

Assessment

See the Evaluate portion of lesson.

Modifications

  • A different experiment can be designed in the Elaborate section.
  • The experimental design graphic organizer can be edited for any motor-skill deficiencies by making it larger or able to be typed on.
  • All basic modifications can be used for these activities.

Alternative assessments

Make necessary adjustments for different experiments.

Supplemental information

This is a list of all the attachments used in this lesson.

Experimental design graphic organizer
Open as PDF (114 KB, 2 pages; also available as Microsoft Word document)
Experimental design vocabulary organizer
Open as PDF (13 KB, 1 page; also available as Microsoft Word document)
Experimental design: Explore worksheet
Open as PDF (37 KB, 1 page; also available as Microsoft Word document)
Experimental design: Explain worksheet
Open as PDF (5 KB, 1 page; also available as Microsoft Word document)
Pepsi-Coke data calculations
Open as PDF (68 KB, 2 pages; also available as Microsoft Word document)
Pepsi-Coke data table
Open as PDF (116 KB, 1 page; also available as Microsoft Word document)
Experimental design evaluation assignment
Open as PDF (85 KB, 1 page; also available as Microsoft Word document)
Experimental design vocabulary definitions
Open as PDF (36 KB, 1 page; also available as Microsoft Word document)
Pepsi-Coke experimental design graphic organizer example
Open as PDF (114 KB, 2 pages; also available as Microsoft Word document)

Critical vocabulary

independent variable
the part of the experiment that is controlled or changed by the experimenter
dependent variable
the part of the experiment that is observed or measured to gather data; changes because of the independent variable
control
standard of comparison in the experiment; level of the independent variable that is left in the natural state, unchanged
constant
part of the experiment that is kept the same to avoid affecting the independent variable
hypothesis
educated guess or prediction about an experiment’s results
qualitative observation
descriptive observations such as color or texture
quantitative observation
measurable observations
inference
the act of reasoning from factual knowledge or evidence

Comments

This is the first lesson in the Critical Thinking in Science unit. The other lessons continue using the vocabulary and the experimental design graphic organizer while teaching the eighth grade content. Students design their own experiments to improve their ability to approach problems and questions scientifically. By developing their ability to reason through problems they become critical thinkers.

  • Common Core State Standards
    • English Language Arts (2010)
      • Science & Technical Subjects

        • Grades 6-8
          • 6-8.LS.3 Follow precisely a multistep procedure when carrying out experiments, taking measurements, or performing technical tasks.

North Carolina curriculum alignment

Science (2005)

Grade 8

  • Goal 1: The learner will design and conduct investigations to demonstrate an understanding of scientific inquiry.
    • Objective 1.01: Identify and create questions and hypotheses that can be answered through scientific investigations.
    • Objective 1.02: Develop appropriate experimental procedures for:
      • Given questions.
      • Student generated questions.
    • Objective 1.04: Analyze variables in scientific investigations:
      • Identify dependent and independent.
      • Use of a control.
      • Manipulate.
      • Describe relationships between.
      • Define operationally.
    • Objective 1.05: Analyze evidence to:
      • explain observations.
      • make inferences and predictions.
      • develop the relationship between evidence and explanation.
    • Objective 1.06: Use mathematics to gather, organize, and present quantitative data resulting from scientific investigations:
      • Measurement.
      • Analysis of data.
      • Graphing.
      • Prediction models.
    • Objective 1.08: Use oral and written language to:
      • Communicate findings.
      • Defend conclusions of scientific investigations.
      • Describe strengths and weaknesses of claims, arguments, and/or data.