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VARIABLES
Grades 7-9

Overview

This lesson is the opening lesson in preparing students to create their own science fair projects. It will introduce the concepts necessary to create an experiment that uses the principles of the scientific method. It gives the students the necessary tools to discriminate between an experiment and a demonstration. The students need to already have been introduced to the steps in writing lab reports using the scientific method: Purpose, Research, Hypothesis, Procedure, Analysis and Conclusions.
ITV Series
Scientific Eye Series III, Lesson Eight, Variables
Learning Objectives
After completing this lesson the students should be able to identify the independent variable, dependent variable and controls in an experiment; and design simple experiments that use controls to isolate a single independent variable and measure the resulting dependent variable.
Materials
Each group of two to four students will need :
Have a classroom source of:
Pre-Viewing Activities
Have the student groups fill two cups with marbles, two cups with fine, dry sand and three cups with water. Have the groups count how many marbles are in each of the two cups. Record group results on the board. Then ask the students to discuss why there are differences in the answers.
Focus Viewing
The focus for viewing is a specific responsibility or task(s) students are responsible for during and after watching the view to focus and engage students' viewing attention. Assign each student group a focus for viewing activity an tell them that they will be standing and presenting their focus for viewing to the rest of the class after viewing the video segments. Group one should identify independent variables shown in the video. Group two should identify dependent variables in the video. Group three should identify controls used in the video. Group four should identify the various devices used to measure dependent variables
Viewing Activities
Teacher note: Several segments are skipped because they do not deal directly with variables or controls and could side track or confuse students who are approaching the topic for the first time. Because of the introduction of vocabulary terms not included in the video, the video needs to be stopped frequently and the students assisted with associating the vocabulary terms with the words and scenes in the video.
BEGIN playing the video from the opening credits. PAUSE the video when the screen shows a picture of a metronome and the narrator says "Look and listen carefully, what's changing here?" mute the sound on the TV and ask the students to focus on what's changing. RESUME playing the video with the sound off. PAUSE the video when the screen changes to a frying pan and have the students discuss what they interpret to have been happening in the segment. REWIND to the beginning of the metronome segment and play it again with the sound on. PAUSE the video when the screen again shows a frying pan. Have the students discuss how their explanations compared with the narrators explanation. Help the students associate the term "cause" with the vocabulary term "independent variable" and the term "effect" with the vocabulary word "dependent variable. FAST FORWARD the video to a screen showing the word "Look" and RESUME playing. PAUSE the video when the screen shows three balloon and the narrator says "Which ones were important?". Have the students identify the three variables assisting them with using cause and effect to determine the independent and dependent variables. These are color and size (independent variables) and loudness of the sound of the balloons bursting (dependent variable). RESUME playing the video. PAUSE the video when the narrator says "There's some vinegar in the left-hand beaker." Have the students identify the things in the demonstration on the screen that are the same. Help them associate these with the vocabulary term "controls". RESUME playing the video. PAUSE when the screen shows bubbles in the left had beaker and point out the independent variable (the vinegar vs. water) and the dependent variable (fizz vs. no fizz). RESUME playing the video. PAUSE when the screen shows a girl holding a bag of molasses and the narrator says "How would you find out how fast the bag goes?" Initiate a discussion about the connection between the dependent variable and measurements. In a good science fair experiment there are measurements of the dependent variable, not a simple statement of this brand wins. RESUME playing the video. PAUSE when the screen shows a sky with a sun and the narrator says, "Elapsed time is a variable." Initiate a discussion of ways to measure time as a variable. Discuss how elapsed time can be an independent variable or a dependent variable relating it to cause and effect. FAST FORWARD the video to where the Scientific Eye logo appears on the screen and RESUME playing. PAUSE where the screen shows the man measuring the bean and the narrator says, "And how long do you think it would take?" Have the students identify the possible independent variables and list them on the board. Have each group choose one variable and identify how they could use controls to isolate their chosen independent variable and how they would measure their resultant dependent variable. STOP the video after the narrator says "Why is fairness important?" and the Scientific Eye logo appears on the screen.
Post-Viewing Activities
Have the student groups predict which "full" cups have the greater total volume of matter in it, the sand cups or the marble cups. Have them write a procedure to prove or disprove their hypothesis. Be sure that the identify the independent variable, the dependent variable and any controls that they use. Check for utilization of the lesson concepts in the design of their experiment by questioning the groups about their procedure. Have the student perform their experiments and record the results. Be sure they unit label the measurements they take to record their dependent variable results. Have them record their results on the board and discuss the results of the class as a whole.

If time permits, have the groups make an extra copy of their experiment and exchange experiment plans with another group. After performing the other group's experiment, have them critique the experiment plan. This will give them experience needed to evaluate their own work. These critiques should be included in the final scores for the activities. This activity lends itself easily to inclusion in a portfolio.
Action Plan
Have the students attend the Mentors program meetings sponsored by Science Pioneers to provide them with real scientist mentors as advisors for their science fair projects. Science Pioneers has offices at Midwest Research on Volker Boulevard in Kansas City, Missouri.

Have the student groups prepare a lesson on designing an experiment to show to a group of younger students. This is particularly useful if you have eighth grade students in a middle school present ideas to a group of sixth graders who are entering science fair for the first time.
Have student groups prepare a sample science fair display from their experiment and have them present it at the next P.T.A. or S.A.C. meeting for parents to get an opportunity to interacts with the students about their science and math experiences. This will be particularly useful if your students are expected to explain their project to the judges at your local science fair.
Extensions
Language Arts and Science:
Have your students as a class videotape a "how to" video for next year's class to see explaining how to design a science fair experiment and identifying the variables and controls in the experiment. This is also a useful review and reinforcement tool for students who have been absent or need further advice in preparing their science fair project.

Language Arts, Science and Graphic Arts:
Have groups write a "how to" manual for placement in the school library explaining how to do a specific science fair experiment and identifying the variables and controls in the experiment. This is also a useful review and reinforcement tool for students who have been absent or need further advice in preparing their science fair project.
Math and Science:
Have the groups make individual group graphs of the results of their data. Have them then make a combined graph of the results of the class for comparison.

Social Studies and Science:
Have the groups locate information in the library about famous experiments, for example: Millikin's oil drop experiment. Have them write make believe lab reports about the experiments utilizing the information given in the written accounts.

If your students have access to Internet or satellite broadcast exchange programs, they will enjoy the opportunity to share their ideas with other classes of students from other schools.

Master Teacher: Joyce M. Conner

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