Tires or Tracks

Physical Science Grade band 3-5 – Benchmark C: Describe the forces that directly affect objects and their motion.
Science and Technology Grade band 3-5 – Benchmark B:  Describe and illustrate the design process.
Scientific Inquiry Grade band 3-5 – Benchmark B:  Organize and evaluate observations, measurements and other data to formulate inferences and conclusions.
Grade band 3-5 – Benchmark C:  Develop, design and safely conduct scientific investigations and communicate the results.
Design Grade band 3-5 – Benchmark A:  Describe and apply a design process to solve a problem.
Grade band 3-5 – Benchmark B: Describe how engineers and designers define a problem, creatively solve it and evaluate the solution.
Grade band 3-5 – Benchmark C: Understand the role of troubleshooting in problem-solving.
Patterns, Functions and Algebra Grade band 3-4 – Benchmark G:  Describe how a change in one variable affects the value of a related variable.
Grade band 5-7 – Benchmark J: Use a formula in problem-solving situations.
Data Analysis and Probability Grade band 3-4 – Benchmark A: Gather and organize data from surveys and classroom experiments, including data collected over a period of time.
Grade band 5-7 – Benchmark E: Collect, organize, display and interpret data for a specific purpose or need.

The goal of this investigation is to evaluate the performance of tires and tracks using a  Mindstorm Lego robotic vehicle.  The performance of the robotic vehicles will be evaluated by testing how they move over various types of terrain and inclines.

For this investigation, students will be asked to modify a robotic vehicle with tires that can move in a straight line over various courses with different types of terrain and inclines.  The students will make measurements of the time it takes for their robotic vehicles to travel a fixed distance from starting line to finish line for each of the four courses.  The robotic vehicle should not be modified until it has been tested three times on each of the four courses.  At least one of the obstacles should be large enough that a robotic vehicle with tires cannot pass over it (examples provided in Appendix G).

  1. The first course will be smooth and flat.
  2. The second course will be smooth and have a steep incline of approximately 30 degrees.  The angle of the incline should be large enough that most of the students’ robotic vehicles with tires cannot travel up the incline without slipping.
  3. The third course will have obstacles such as trenches or speed bumps that the robotic vehicle must travel over to reach the finish line.
  4. The fourth course will be flat a littered many small objects such as dry beans strewn across it.  The quantity, size and shape of the objects should be chosen to cause slippage of robotic vehicles with tires.

Following tire terrain trials, students should now have a discussion about the performance of their robotic vehicles with tires over the four courses.  From this discussion, the students should create a list of criteria for a “better” robotic vehicle.  Some possible criteria include: finishes the race, speed, and travels in a straight line.

The students should now modify their robotic vehicles so that they have tracks instead of tires.  The design of the new robotic vehicles with tracks should take into account the students’ criteria for a “better” robotic vehicle.  The students should then test their new robotic vehicle three times on each of the four courses, measuring the time from start to finish for each test.

In conclusion the teacher will lead a post activity discussion to address critical thought questions such as; which design is faster, which design affords the robot most success with obstacles, which design is most reliable, how does the engineering design process help you to explore and solve this problem, why was it important to identify variables and conditions and not modify the throughout testing.

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