If possible, keep an example of Merry-Go-Round Model A6 for students to compare with Merry-Go-Round Model A7.Ħ. Students should be made aware that the angled gearing enables the rotary motion to be transmitted through a 90-degree angle. The gear ratio is 3:1 this is a gearing down arrangement (because 24/8 = 3/1), and the merry-go-round turns slowly. The students will have to crank the handle three times for Merry-Go-Round Model A6 to turn once. Students must write their answer on the student worksheet. Encourage them to try more than once, to ensure that their observations are correct. Have students observe the starting point of both the handle and the minifigure. If you want Sam or Sally to make a full turn, how many times must you crank the handle? For the prediction, the correct answer is model A7 however, it does not matter whether students get the answer right or wrong at this point, only that they should make a prediction that can be checked later. If I compare model A6 to model A7, then I think Merry-Go-Round Model (A6/A7) will turn faster.Įncourage students to discuss the effects the different gearing has on the merry-go- rounds in their own words. Next, look carefully at the pictures of the models and make a prediction. Students should notice the difference in both size and number of gears used on model A6 compared to model A7.Ĥ. What do you notice? Explain how the models are different. Then look carefully at the pictures of the models and compare Merry-Go-Round Model A6 to Merry-Go-Round Model A7. There are two gears used in model A6: a spur gear (8 teeth) and a crown gear (24 teeth).ģ.
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