Grade 4 Science - Pulleys and Gears

To make the gears portion of the Pulleys and Gears portion of the unit more "hands-on" I planned 4 workstations.

Workstation 1 - Spur Gears

The first workstation uses gears with different numbers of teeth so that students can see how gears can be used to change the direction of force and to increase or decrease the speed by using gears with different numbers of teeth.

Student Worksheet: https://drive.google.com/open?id=127K0aR-6KrsC0mQ_fdtQkJPxJCT4qW42OitjffAa-fw

Gears can Change Direction

Workstation 2 - Bevel Gear

This workstation uses Lego gears from Lego Mindstorms to illustrate the functionality of a bevel gear which changes the direction of the force. Technically this isn't exactly a bevel gear but it functions the same and illustrates how the force direction is changed by 90 degrees.

Student Worksheet: https://drive.google.com/open?id=1PdL-7OdU79vX5J3dGB5BKbHDsPTUFY1EFqfKM-2zmEs

Gears can Change Direction

Workstation 3 - Worm Gear

This workstation uses Lego gears from Lego Mindstorms to illustrate the functionality of a worm gear. The worm gear also changes the direction of the force by 90 degrees like the bevel gear but can apply a much greater force and from the small wheel to the large wheel while not allowing a force from the large wheel to be applied back to the small wheel.

Student Worksheet: https://drive.google.com/open?id=1IPeHEEjwuAS5V54pn23z4u135_pxNQmN6s6Kd2_WSMA

In music class, we had been learning to play the Ukulele and a couple of the students observed that the tuning machines on the ukulele were worm gears.

Gears Applying Great Force

Workstation 4 - Multiple Spur Gears

This workstation uses Lego gears from Lego Mindstorms to illustrate how combining gears of different sizes (with different numbers of teeth) can greatly increase the speed or power that is beeing transfered.

Student Worksheet: https://drive.google.com/open?id=1lIRzE9-0EXnjt1opwsmeZhbsAe_-QvZGZh4CZRHDtns

Combining Gears to Increase Speed

Resources

Gear Generator https://geargenerator.com allows you to define gears and specify their number of teeth. You can make coaxial gears as well as internal gears or simply gears whose external teeth mesh.

 

This video is helpful for illustrating how different size cogs at the pedal and back axle can affect the speed and performance of a bicycle.

How Bicycle Gears Work