Good examples of it are falls of metal or glass solid balls, as opposed to a sheet of paper which is initially in a horizontal position. Even taking a styrofoam ball you may notice an air resistance comparing its fall with a fall of solid metal ball. An obvious qualitative observation for motion of all mentioned above balls and many other compact objects is a gradual increase in their speed in the initial phase of the motion. Taking quantitative data, like covered distances for different times, is more difficult. Photogates, ultrasonic rangers or other suitable technologies are needed.
Human beings have too slow reflex for that kind of measurements on the surface of our planet.
This is only real obstacle because nowadays almost every wrist watch with digital display has a stopwatch of accuracy of 0.01 s. Our reflex, however, has accuracy of about 0.1 - 0.2 s, and this is not good enough to make meaninfull measurements. Now you should comprehend why ancient and medival scientists had difficulties with understanding even simple motions. They were deprived of reliable experimental data. If you have not enough money to buy one of the mentioned above technologies, but you still have good enough computer, imagine yourself a different planet with much lower gravitational pull.