Sheryl Sandberg once told an employee she sounded stupid - and the reason why is a great management lesson for everyone

Kim Scott is a professional coach for tech companies like Twitter and Qualtrics. And before that, Scott worked for a number of high-profile companies including Apple and Google.

At venture capital firm First Round Capital's recent CEO Summit, Scott talked about how to make sure you're providing the right type of guidance to your team and being a good boss.

Scott uses an approach called radical candor, and she used an example from her time working for Sheryl Sandberg at Google to illustrate it to her audience.

Scott had just wrapped up delivering a presentation about Google's AdSense business to Larry Page, Sergey Brin, and Eric Schmidt.

She felt really good about the presentation: "When we told Larry, Sergey and Eric how many publishers we had added over the previous months, Eric almost fell off his chair and asked what resources they could give us to help continue this amazing success," she said in a recent blog post for First Round Capital.

But then, Sheryl Sandberg, Scott's boss, took Scott on a walk. Though the presentation went well, she told Scott, "you said um a lot."

"And I thought, 'Oh, no big deal. I know, I do that,'" Scott recalled. "But who cared if I said 'um' when I had the tiger by the tail?'"

Scott continued to downplay Sandberg's attempts to help with her conversational filler problem, who even suggested that Google hire a speaking coach to help her. But then, Scott says, Sandberg did something that got her attention.

"Finally, Sheryl said, 'You know, Kim, I can tell I'm not really getting through to you. I'm going to have to be clearer here. When you say um every third word, it makes you sound stupid,'" Scott said in the blog post.

Sandberg may have spoken bluntly, but she got the point across. Needless to say, Scott ended up taking Sandberg up on her offer, and Google even hired a speaking coach to help her eliminate her conversational fillers.

"If she hadn't said it just that way, I would've kept blowing her off. I wouldn't have addressed the problem. And what a silly thing to let trip you up," Scott said.

After the fact, Scott reflected on what made Sheryl Sandberg such a great boss at Google. Her conclusion is her theory of radical candor - a skill that requires bosses to simultaneously care personally and challenge their employees directly.

You can watch Scott's entire presentation at First Round's website.