Trial and Error

What’s good enough?


No machine is perfect. Engineers do their best to make them as precise and accurate as possible, but there will always be some degree of error.

What factors determine the amount of error that’s acceptable?

Build this *Bevel Bot*.


It’ll help you investigate which aspects of its design and program can cause inaccuracies.

Do a test run.

EV3 Classroom-Programs 2-1-program en-us

Place the model on a solid and level surface, and mark its starting position. Run the program and mark the finishing position once it’s stopped moving.

Does the Bevel Bot move 100 cm? Are the calculated motor rotations, the actual motor rotations, and the calculated distance traveled (in cm) displayed?

Record your results.


Record the experiment number, calculated distance traveled, and measured distance traveled in a testing table. Make sure to leave enough space for additional columns for further calculations.

Perform the experiment using the default model and program. Repeat the experiment for each adjustment that you make to determine its effect.

Summarize your results.


Use the average measured distance traveled for each of the adjustments you’ve made and calculate the error to identify which version was the most accurate.

Which adjustments to the robot’s design and program had the biggest impact on its accuracy?

How did you do?


What did you do well? Is there anything you could’ve done better?

Awesome! Now you know how to improve the accuracy of a robot. Let’s move on to the next lesson.