California Career and Technical Education Standards

• ED.D.D4.3 Know the six simple machines and their applications.
• ED.D.D4.5 Solve problems by using the appropriate units applied in mechanical, electrical,...
• ED.FS.11.0 Demonstration and Application
• ED.FS.5.3 Use critical thinking skills to make informed decisions and solve problems.

California Academic Content Standards (Reinforced)

• ELA.9-10.R.CAGT.2.3 Generate relevant questions about readings on issues that can be researched.2
• ELA.9-10.R.CAGT.2.5 Extend ideas presented in primary or secondary sources through original analysis...3
• ELA.9-10.R.CAGT.2.6 Demonstrate use of sophisticated learning tools by following technical direction...2
• M.7.AF.1.1 Use variables and appropriate operations to write an expression, an equation, an...23
• M.7.AF.4.2 Solve multistep problems involving rate, average speed, distance, and time or a ...22

• Robot Race - Hooks / Set

  Vex robot race video is cued up on the projector.  The following questions are on the board:  Why do these robots have different speeds?  What specific mechanical factors might cause differences in speed?

   As students enter the room they pick up their notebooks from the book shelf.  As students sit and open their notebooks the video is started.  After watching the video students brainstorm answers in pairs and write their answers in their notebooks.

  • Exothermic Drag Race [ Watch Video ] [ Download Original Video ] Video of Vex Robots Racing in Autonomous mode
• Discussion Based on Brainstorming - Other

  The teacher leads a short discussion about the brainstorming.  Discussion may include replaying the video to look at specific student ideas.    Possible reasons students might list:  battery charge, friction, bearings, wheel sizes, construction quality, motor selection, programming issues, gears, gear ratios. 

  • Java Applets for mechanisms(animations) [ Go to Site ] another great source of simple animations that illustrate different kinds of geared mechanisms
• Gear Ratios - Lecture

  Once the students have ideas about possible causes of speed variation, I will validate all of the ideas and tell the students we are going to focus on gears and gear selection.  I will instruct students to take notes as I go over how to control speed using gears.  The attached power point covers changes in direction and gear ratios.  After the showing the power point I check for understanding.  Ask students to give examples of gear selections based on proposed outcomes.

  For example:  I want the robot to go faster, but I want the wheels to rotate in the same direction as the motor.  How many gears do I need?  Which gear should be larger and which gear should be smaller, the input gear or output gear?

  • Gear Ratio power point [ Download ]
• Gear Calculation - Demo / Modeling

  I will work through a sample calculation to demonstrate how to choose gears for specific outcomes.

  The sample calculation will be based on using input data from last years USFIRST robot.  Students will be given a set of specifications for the motors, gears, and wheels for the VEX robots.  In the next activity they will use my example and the specifications to solve for a given speed on a VEX robot.

  The sample calculation needs to be done based on lab materials and will up-loaded in the future.
• Student Design/Problem Solving - Group Work

  Students will be in groups of three.  Each group will be given a specification sheet and a copy of the rubric.  Each group will go through the calculation process to determine the optimal gear choices to achieve the specified speed.

  Spec sheet needs to be developed and up loaded
• Students Build a VEX Robot. - Projects

  Students will build a VEX robot based on the criteria they have decided on as a result of their engineering calculations.  One set of VEX robots will needed for each team of students.