Maybe it's not the best method but when I first starting integrating my young ones with the established hens, I would shoo them with a soft switch. To be honest it started with me picking up a kale plant they had stripped all the leaves off. I certainly don't hit them with it, just a gentle shoo shoo sweep. Still got that tired kale and they know when I pick that up it's time to go it. I usually have a bribery/reward of treats in the coop for them too which helps. Frankly anything visible or a consistent sound, and they'll learn. We have hawks too, so no nonsense when it's time to go!