Straight Line Motion with Constant Velocity
Although speed and velocity mean different things when used technically by a physicist, for now we'll use them interchangeably, both referring to rate of travel, or how much distance one covers in a given time. An example of motion at constant speed would be traveling on a straight line down a highway while the speedometer of your car remains fixed at, for example, 30 m/s (about 67 mph). The concepts that apply for travel at constant velocity also work for travel at a known average velocity, too.
Below is a college group doing a measurement lab for a sledge moving at constant velocity: