Identifying Variables Lesson Plan

Instructor: Joanne Abramson

Joanne has taught middle school and high school science for more than ten years and has a master's degree in education.

This lesson plan introduces experimental variables to secondary students. Students watch and discuss a demonstration and short video, and then apply their learning to an experimental investigation.

Learning Objectives

By the end of this lesson, students will be able to:

  • define the term 'variable' as it relates to scientific experiments
  • define the terms 'independent variable,' 'dependent variable,' and 'control variable
  • identify the independent variable, dependent variable and control variable in an experiment


1-1.5 hours

Curriculum Standards


Determine the meaning of symbols, key terms, and other domain-specific words and phrases as they are used in a specific scientific or technical context relevant to grades 9-10 texts and topics.


Analyze the structure of the relationships among concepts in a text, including relationships among key terms (e.g., force, friction, reaction force, energy).


Initiate and participate effectively in a range of collaborative discussions (one-on-one, in groups, and teacher-led) with diverse partners on grades 9-10 topics, texts, and issues, building on others' ideas and expressing their own clearly and persuasively.

Key Terms

  • Independent variable
  • Dependent variable
  • Control variable


  • Candle
  • Matches or lighter
  • Funnel
  • Water
  • String of various thicknesses (such as kitchen string, yarn, fishing line and dental floss)
  • Straws of varying diameters
  • Balloons of different sizes and shapes
  • Different types of tape
  • Card stock or construction paper
  • Scissors
  • Meter sticks
  • Stopwatches


Preparation and Warm-up

  • Set up the construction materials (string, straws, balloons, tape, and card stock) around the room so that students will have access to them during the activity.
  • Prepare for the demonstration by placing 2 balloons, a candle, matches, funnel and some water near the front of the class room.
  • Begin the lesson by asking for a couple of volunteers, one to write student responses on the board, and one to hold the balloon.
  • Blow up one balloon and tie off its end. Hand it to a student to hold, and then light the candle. Ask students to predict what will happen when you touch the candle flame to the balloon. Have your student volunteer hold out the balloon and test their predictions.
  • Now, using the funnel, add some water to the second balloon. Blow up the balloon and tie off the end. Ask the following question (have your other volunteer write both the question and the responses on the board):
    • What are we changing?
  • Hand the balloon to your first volunteer and ask students to predict what will happen when you hold a candle flame to the balloon this time. Ask the following questions (again, write both the questions and the responses on the board):
    • What are we testing?
    • What is staying the same?
  • Ask your first volunteer to hold out the balloon and bring the flame to the balloon a second time (be sure to hold the flame against an area with water). Allow students some time to share their observations and hypothesize about what happened.
  • Return to the questions on the board and explain to the students that each question refers to a type of experimental variable. They will be learning more about experimental variables in today's lesson.

Video Lesson

  • Begin the video Identifying & Interpreting Independent & Dependent Variables. Pause at 1:29 and ask the following discussion questions:
    • What is an experiment?
    • Why is it important to make an experiment repeatable?
  • Continue the video, this time pausing at 3:40. Ask students the following questions:
    • What is a variable?
    • What are the three types of variables discussed in the video?
    • How do they get their names?
  • Return to the video. Pause at 6:49 and read the following scenario and ask the accompanying questions:
    • You want to see which brand of miniature car has the best axle bearing. To do this, you set up a ramp and time how long it takes each brand of car to travel 1 meter.
      • What is your independent variable?
      • What is your dependent variable?
      • What is one of your control variables?
  • Continue the video and watch it to the end. To check for understanding, display and complete the lesson quiz.

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