This video is a reminder about how to calibrate the color sensors attached to a LEGO EV3 Robot.
LEGO MindStorms EV3 Color Sensors are incredibly sensitive to variations in light that we would not necessarily notice ourselves. In practice, it is necessary to calibrate the Color Sensors of a LEGO EV3 Robot at the start of each Robotic session. Even though these EV3 color sensors are an improvement on the old Light Sensors supplied with the previous LEGO MindStorms NXT sets, they still need to be re-calibrated regularly. A streak of sunlight across the floor near a Robot can often cause your Robot to behave erratically. We have also found that windows without curtains in the room we are using, can contribute towards the light on the floor changing, because clouds passing in front of the Sun can cast shadows. You will get a lot of practice in calibrating your Color Sensors.