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What Goes Up Must Come Down!
Lesson Plan

Summary: What Goes Up Must Come Down! is a controlled investigation which asks the question, "What will happen if objects with different masses are dropped at the same time?" Students hypothesize about the nature of falling objects, design an experimental test to answer the question using everyday objects, analyze data to form conclusions, and infer that mass does not affect the speed of falling objects. This activity culminates with the teacher demonstration (dropping a bowling ball and a golfball) to show that mass does not affect the speed of falling objects.

Day 1: Gathering Information and Designing a Test (45 min.)


Get Set!!!

  • Display the bowling ball and golfball to the class and ask, "What will happen if these two objects are dropped at the same time?"
  • Discuss the possible outcomes (bowling ball wins, golfball wins, tie).
  • Direct students to close their eyes and put their heads down to take a class survey (bowling ball, golfball, or tie).
  • Distribute the Thinksheet and direct students to fill in the class survey results.
  • Discuss the terms mass, speed, and gravity and have students record their meanings.
  • Direct students to complete the "Hypothesis" section of their Thinksheet.
  • Explain how this activity is grouped:
    • discussion
    • experiment to identify a test that will allow objects to be dropped at the same height and time
    • experiment using the selected test design
    • discussion
  • Display a student materials bag. Explain to students that they will use items from this bag to design a test for studying the effect of gravity on falling objects.
  • Discuss variables that must be followed during experimentation in order to have a fair test.
Control Variables
(must be kept the same)
Treatment Variable
(the ONE thing that changes)
  • Drop objects from the same height
  • Drop objects at the same time
  • Use objects that aren't affected by air resistance
  • Objects dropped will have different masses
  • Demonstrate the problem of air resistance by dropping a piece of paper and a golf ball at the same time.
  • Distribute one bag of materials to each team of four students and allow time for them to come up with a test that they feel is fair. Note: Common tests students use include: a two-hand drop holding objects from above, a one-hand drop holding objects from above, a one-hand drop holding objects in the palm of a hand.
  • Gather students into a floor group and have each team demonstrate their test. Discuss an advantage and disadvantage for each test. Examples are listed below.
Type of Drop Advantage Disadvantage
two-handed, holding from above easy to do hands may not release at the same time
one-handed, holding from above easy to do fingers may release one object before the other
one handed, holding from below objects can be easily held at the same level above the ground hand must be pulled downward faster than the pull of gravity

Day 2: What Will Happen If Objects with Different Masses Are Dropped at the Same Time? (45 min.)

  • Review information from the previous day's lesson. Remind students of the test design that was selected for all teams to use.
  • Distribute the Data Sheet (see Ready to Print). Discuss the importance of recording consistent results (i.e., When testing the tennis ball and paper clip, record a result after several trials have been conducted and a pattern of results is established).
  • Distribute one bag of materials to each team of four students and allow time for them to test five to ten pairs of objects using the selected test design.

  • Demonstrate several trials of the bowling ball and golfball drop outdoors. Note: Be sure to select a location with a soft landing surface (i.e., soil, not concrete!).
  • Complete the "Make Sense of It" section of the Thinksheet.
    • Discuss team results and complete the Summary of Class Results (at the bottom of the Data Sheet) together.
    • Direct students to write a conclusion based on the Summary of Class Results. Note: Students can accept or reject their hypotheses. They can also accept the null hypothesis (i.e., no conclusion can be drawn from the data collected).
  • Summarize the Main Points
    • Mass is the amount of matter in an object
    • Gravity pulls on all objects the same regardless of mass
    • When variables are controlled, objects with different masses fall at the same speed
  • Compliment students for appropriate behaviors during the lesson.
  • Evaluation
    • Formative: anecdotal notes of teams in progress, incidental questioning of students' rationale for what they are doing (during activity), observation of teamwork, status of the class (end of each unfinished activity day)
    • Summative: Choose one or more of the following (see Ready to Print)
      • Online Assessment
      • Team Evaluation

Want Something More???
  • Check out Related Resources. for additional information.
  • Create a double bar graph the Class Survey (before the experiment) and Summary of Class Results (after the experiment).
  • Record the bowling ball and golfball drop and play back the video for the class in slow motion.
  • Prove to your students that a sheet of paper and a marble will fall at the same speed if variables are controlled. First, drop the sheet of paper and the marble (the marble will win). Next, fold up the sheet of paper until it will fit into a film container, and place the marble in a second film container. Now, drop the two film containers, and voila, they will fall at the same speed (the variable of air resistance has been controlled)!