When you interconnect your bricks, the structure will not fall apart when you move it.Ģ. Ask what the gear ratio is, and how much faster or slower than the handle the merry-go-round will turn.Here are some tips for building with basic LEGO bricks, beams, and axles. With more advanced students, you might consider introducing compound gearing or gear ratios. For inspiration, read or show the “Overview: Gears” section. It is suggested that students should draw a gear train (many gears meshing) or items where they find gears used in everyday machines and mechanisms. What did you do to make sure your observations were correct? How many times did you have to turn the handle to make the merry-go-round turn once? Why do you think that was? There are no building instructions included to guide students through the Continue phase, other than the illustrated suggestions on the student worksheet.Įncourage your students to discuss the effects that the gearing in focus will have on the merry-go-round in their own words, prompting them with questions such as:ĭescribe what happened when you turned the handle. Students are encouraged to explore the gearings illustrated on the student worksheet and to record their observations. The intention is to help students reflect on what they have done well and what they could have done better. Each rubric includes four levels of achievement. Students use the self-assessment rubric to evaluate their work. Merry-Go-Round Model A7 turns faster because of the gearing-up arrangement with the 40-tooth drive gear and the 24-tooth driven gear. Finally, draw a conclusion and check your prediction. It is recommended that students work in pairs one student can observe the minifigure while the other cranks the handle a full turn.Ĩ. The gear ratio is 3:5 (because 24/40 = 3/5), and the merry-go-round turns at a much faster pace. Three turns of the 40-tooth gear produce five turns of the merry-go-round. Encourage them to try more than once, to ensure that their observations are correct. Have students pay attention to the starting positions of the handle and the minifigure as described earlier. If you crank the handle three times, how many times does Sam or Sally make a full turn? There are four gears used in the model: two small spur gears (8 teeth), a crown gear (24 teeth), and a large spur gear (40 teeth). Build Merry-Go-Round Model A7 and make it turn.įollow Building Instructions A, pages 44 to 52, steps 1 to 11.Įncourage students to identify the gears and count the teeth on the gears. 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. 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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