Have you ever wanted to get ideas out of people, but they froze up and couldn't give you something meaty? For instance, perhaps you've just held a training session and you'd like to know what they valued. When you ask, they say “everything.” Or you ask what they would like changed and they say “nothing” or “I don't know” or they don't respond at all.
When you insert the small, but powerful, phrase “one of the things” into your sentences, you are guaranteed to reap many more answers. The idea of naming one thing gives peoples' brains permission to come up with something concrete.
So instead of “What did you value in class?” you say “What is one thing that you value from the class?” or “What is one of the things you'd like changed in the training?”
Yes, you may want more than one ... and you may very well get more ... but the question phrased as asking for one is the magic for releasing the ideas. Everyone can come up with a single item.
And very often, the one thing they tell you, will be the most important