Peak Performance





Name of Activity Peak Performance
Author Jay Clark
Keywords NXT, car, course, fastest, flat, inclined, gear, gear ratios, torque, speed, optimization, building, drive gear, driven gear, 1 Hour Total
Subject NXTs
Grade Level K, 1, 2, 3, 4, 5, 6, 7, 8, 9+
Time 1 Hour Total
Brief Description Students must gear their NXT car to complete the course the fastest. The course consists of a flat section and an inclined section.
Lesson Objectives: To learn about gear ratios, gearing for torque vs gearing for speed, optimization, and building.
Materials Needed: NXT kit
Computers running MINDSTORMS
Preparation and Set Up: Prepare one or more courses – With a flat beginning and an incline ending. The length of both sections will determine the optimum gear ratio. To allow for extensions, set up other courses with varying distances of the course components.
Necessary Background Using gear ratios students can gear their cars for more torque or more speed. If the drive gear is bigger than the driven gear, the car will be geared for speed. If the other way around, it will be geared for torque.

A car geared for torque will be slower, but will climb better. A car geared for speed will be quick, but might not be able to climb the ramp.


Gear Ratio – The ratio of the speed of rotation of the drive gear of a gear train to that of the driven gear.

Drive Gear- The gear attached to the source of torque. (Usually the motor).

Driven Gear – The gear that receives motion from the drive gear.

Optimization – Finding a balance between design concerns that yields the best solution.

Procedure Introduction – 10 Minutes Ask students if they’ve ever used gears before. More than likely, they’ve driven a 10 speed bike before, and never knew how the gears worked. Introduce students to gears and gear ratios. Using a pre-made gear train, show them the size of the drive gear and the driven gear, and ask if the driven gear will spin faster or slower than the drive. If they are having trouble seeing it, ask them for every one rotation of the drive gear, how many times does the driven gear rotate? Explain torque vs. speed. ie. tugboats – high torque, low speed. Handheld fans- high speed, low torque. Introduce the concept of optimization. Introduce the activity Activity – 40 minutes Clean up/ Wrap up – 10 minutes

  • What was easiest? What was hardest?
  •  What would you have done differently?
  •  What were some good ideas you saw that other groups came up with?
Extensions: Have the students try a different course with different dimensions and slopes.
Reference 1
Reference 2






Name of Activity Tug-O-War
Author Kara Miranda
Keywords gear, gear ratios, build, machine, tug-o-war, competition, prototype, Engineering Design Process, torque
Subject NXTs
Grade Level 4, 5, 6, 7, 8, 9+
Time 3 Hours Total
Brief Description Students will use their knowledge about gears and gear ratios to build a machine that will play tug-o-war against another classmate’s.
Lesson Objectives: To apply building techniques and knowledge about gears to an activity challenge.
Materials Needed:
RCX or NXT LEGO kits

Assortment of extra LEGO pieces, especially gears and beams
Engineer’s Planning Sheet

Preparation and Set Up:
Collect necessary materials
Photocopy worksheets
Arrange students into groups of 2
Decide how you will distribute extra pieces
Write design requirements on the board
Necessary Background Review gears, gear ratios, and torque.

Engineering Design Process

Gear ratio

    • Tell students that in this challenge they will be playing tug-o-war by building a machine that can provide enough torque to pull on another machine doing the same thing. String will be tied between the two, and a machine will have to pull the other over a line of tape in order to win.
    • Make sure to review how gears work, gear ratios, and using gears for torque vs. speed. Also explain the engineering design process.
    • Tell students the requirements for their tug-o-war contenders. Examples of requirements are:
    •       Must use gears
    •       Must have a sensor
    • Allow the class to brainstorm different ideas for their machines. Have them plan out and draw their design on the engineering planning sheet.
    • Distribute materials and have students start building. You may have to assist students with tying string to their machine.
    • After the students finish building, pair up machines and tie them to either end of a string, making sure the middle of the string is right above the tape on the ground, and that both machines are equidistant from the tape.
    • Have the students start their machines. Whoever’s machine gets pulled over the line first, loses.
  • After the students finish, review the activity with the class. Have them share their ideas, ask groups to explain what the hardest part of the challenge was, etc.
Extensions: Have students add more gears
Make a classwide tug-o-war competition. Whose is the “strongest”?
Allow those who lose to redesign and compete against each other again
Reference 1

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