Hare and Snail Challenges
Students engage in the second design challenge of the unit, which is an extension of the maze challenge they solved in the first lesson/activity of this unit. Students extend the ideas learned in the maze challenge with a focus more on the robot design. Gears are a very important part of any machine, particularly when it has a power source such as engine or motor. Specifically, students learn how to design the gear train from the LEGO® MINDSTORMS® servomotor to the wheel to make the LEGO taskbot go faster or slower. A PowerPoint® presentation, pre/post quizzes and a worksheet are provided.
Engineers alter vehicle designs to move very fast, like hares, or much slower, like a snails.Copyright (jackrabbit) 2007 Ancheta Wis, Wikipedia; (snail) 2013 Derzsi Elekes Andor, Wikimedia Commons http://en.wikipedia.org/wiki/File:JackRabitt,OldFtBliss.JPG http://commons.wikimedia.org/wiki/File:%C3%89ti_csiga_(Helix_pomatia).JPG
Some vehicles (such as race cars) travel very fast, while other vehicles (such as tractors and earth moving equipment) travel slowly. Engineers are responsible for designing all these types of vehicles, and so must consider the very different desired outcomes in performance. What might be different in these two cases? While the associated lesson provides students with an understanding of how the arrangement of gears can be used to design these differently in order to meet each vehicle type's desired performance outcomes, this activity's challenge provides insights into how engineers can help provide flexibility to change speeds and torque in a vehicle using the engineering design process.
After this activity, students should be able to:
- Explain the terms "gear" and "gear ratio."
- Using a LEGO MINDSTORMS Education EV3 Core Set, assemble two gears on a beam to provide motion in a given gear ratio.
- Relate gear ratios to speed and torque of the LEGO MINDSTORMS EV3 robot.