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Simple Machines
Lab 4 - Gears

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Part 1 - Step by Step

  1. InstructInstruct students to use their Data Collection Sheets to gather data on the gears of the Clock build. They will be looking at each gear one by one to compare it with the one after it. Under Gear 1, students will record if it is smaller, larger, or the same size as Gear 2. Journalists will also record if Gear 1 moves faster, slower, or the same as Gear 2. For Gear 2, they will compare it to Gear 3.
    Clock Gears Labeled
  2. ModelModel using a group’s Clock, how to identify the eight different gears. Then model turning the handle, identifying Gear 1, and circling in the data table that Gear 1 is equal to Gear 2 in size and turns. If students are unsure how to identify the movement of the gears, have them find one tooth and focus on that one. If students need to, they can use a pencil to draw a mark on one tooth so they can track that tooth when it moves.
    Video file
  3. FacilitateFacilitate as each group is conducting the investigation. Ensure that each group is correctly identifying all of the gears and comparing correctly. Praise students that are showing good teamwork and collaboration. As you circle the room to check on each group, ask them the following questions:
    1. What are you investigating?
    2. What kind of data is your group collecting?
    Gear sizes
  4. RemindRemind groups that they are doing work as they turn the handle. The gears do work turning the Clock’s hands. As you circle the classroom, ask groups to define work for you. They should know this from previous Labs in the Simple Machines Unit.
  5. AskAsk students to think about whether there is a pattern between the gear size (e.g., the first gear is smaller than the second) and the rate of the gear turning (e.g., the first gear turns more than the second).
    Video file

Mid-Play Break & Group Discussion

As soon as every group has completed their Data Collection Sheet, come together for a brief conversation.

  • What patterns did you notice between gears? Check your Data Collection Sheet and see if you can find any patterns in your data.
  • The first gear is also called the driving gear because it controls or ‘drives’ the next gear. The second gear is called the driven gear because it is being controlled or ‘driven’ by the gear before it. 
  • When the driving gear is smaller than the driven gear, it creates more power. When the driving gear is larger than the driven gear, it makes the gear faster. Did your groups see that extra speed during Play Part 1? 
  • Let’s look at gears 8 and 9.
     

Part 2 - Step by Step

  1. InstructInstruct students that they will add a 9th gear to their clock build, and make predictions for how it will affect the movement of the other gears.

    Will adding a smaller gear make the other gears move faster? or slower? What does that tell you about the work being done by the gear?

    • Each group will make predictions before testing, and write them in the predictions area of the Play 2 section of their Data Collection Sheet.
    • Groups will first add a small red gear and test its affect on the Clock build. Then they will add a larger Pink Gear and test it.
  2. ModelModel how to add the additional 9th gear. Students have to test two different gear options. Option A has students adding a smaller 9th gear than Gear 8. Option B has students adding a gear the same size as Gear 8.
    Gear 9 option
    Option A
    Option B
    Option B
  3. FacilitateFacilitate as each group is conducting the tests of their predictions. Praise students who are using vocabulary words as they are conducting their investigations. Vocabulary to look out for includes:
    • Gears
    • Investigation
    • Prediction
    • Work
    Gear sizes
  4. RemindRemind groups to switch Gear 9 to Option B. Ensure that students follow the same testing process as they did with Option A.
    Gear Option B
  5. AskAsk students how the gears make work easier. If turning driving gears more than driven gears increases strength, what does turning driving gears less than driven gears possibly increase? Students should be familiar with this from Mid-Play Break, but give them the chance to rephrase in their own words.