Among the many hats he wore, Clay Christensen, of disruptive innovation and Harvard Business School fame, was an educator. Few were better.

As Southern New Hampshire University President Paul LeBlanc told the Boston Globe, Christensen was “maybe the best teacher I’ve ever known.” Given the number of educators there, LeBlanc is in a position to know.

Christensen—or Clay, as I called my mentor, friend, co-founder, and coauthor who passed away last week—was a master storyteller. Clay was an expert at weaving the pertinent details of a story together to illustrate a larger truth. Although you’d never guess it from his slow, soft and subdued speaking style, he knew how to land his punch lines. When top professionals—educators, journalists, executives, politicians and the like—asked him questions, he typically answered with a story so that he would help you learn how to think, not what to think.

Given the evidence that human brains are wired to learn through stories, his storytelling skill was a key asset as an educator.

But Clay didn’t stop at a good story. In his class, he made sure that you digested the deeper takeaway behind it—and could then transfer that learning to a range of contexts.

He did so by framing his teachings through questions—which, as he said, “create spaces in the brain for solutions to fall into.” Once again he was leveraging a principle from cognitive science, which is that people are most primed to learn when you start a lesson with a mystery, problem or question that doesn’t make sense—and causes the learners to sit forward and engage.

Each class session he taught started with such a question, but even his entire course was designed around a seminal question: Why do successful organizations fail? It’s a paradox that the theories he taught were designed to help answer.

After students learned a theory by focusing on a particular industry—steel mills were a favorite—the class would often flip open the Wall Street Journal and apply the theory to different industries and companies to cement the learning.

At a business school where takeaways from classes were often benign statements like “people matter,” Clay stood out for how much deeper he went and how the recommendations from his theories changed depending on the circumstance.

His class also changed the way I saw literally everything in the world.

When on a November day he announced at the end of class that anyone interested in coauthoring a book with him about applying those theories to solve the challenges facing public education should stop by, I was intrigued.

I had a meeting with him about a different topic. At the very end, I blurted out that while I didn’t come to business school to write a book—I actually came to get away from public policy and writing, which had been my background—to work with him and his theories on such an important problem would be an amazing opportunity.

He thanked me and said he’d think about it, which he did. We had a few more conversations.

I wasn’t his first choice for the project. But when the woman who was took a different job, in February he said I should plan to stay on after graduation and write the book with him. In his words, the book would take a year to write, and then he would help me land in whatever job I wanted to do next.

That sounded like a generous deal—typical for Clay—but he didn’t really ask whether I was signing up. He just knew we were now doing this together. And so the master educator set out to write about education with his former student.

When all my classmates packed their bags after graduation and left Harvard, I stayed. Clay took the time to meet my parents at graduation. When we were coordinating where to meet on the phone, he said, “I’ll be the one with my right hand in my left pocket”—a typical Clay joke for someone at 6’8” who would be hard to miss.

Within a few days, Clay and I met again, which we had begun to do regularly. At the end he casually handed me a huge stack of papers—about three feet high—and said, this might be useful to you.

Reading the papers afterward, what I began to piece together was that public education was a topic Clay had been thinking about and researching for several years now—and I was just the latest in a line of people to partner with him to tackle it.

That was both reassuring and daunting. He had done a lot of the legwork into the root causes of what ailed public schools. But he had tried to write a book on the topic with others, and it hadn’t come together.

This time proved different—in part because Clay had the patience to extend the timeline for finishing the book to two years instead of one, and in part because he was determined and engaged despite the demands on his time.

My meetings with Clay over the next two years turned into a series of master classes in logic, argumentation, research, writing, management, education, humanity and religion. He told me stories about the biographies he had written about his grandparents so that his children would know of the hardships they had endured, and be able to apply lessons from them. We debated about the underlying costs of education, Baumol’s cost disease and the rise in the price of postage stamps.

We sought to discover whether public schools had reliably improved as organizations in other fields had—or whether they were an anomaly—which ended up with me in the back room of a school district office for several days studying the transcripts of students from the 1950s and 60s. We spent time in his dining room with superintendents and former school board members debating the ideas that emerged in our research. I won’t lie. As a product of public schools, I was gratified that we concluded they had improved and adjusted remarkably to the shifting swings of political interests over the years.

In the midst of writing the book, we also cofounded a non-profit think tank—what’s now called the Clayton Christensen Institute—and set about figuring out what it would ultimately do and how to make it into a sustainable, impactful organization. Starting organizations to address opportunities and challenges was in Clay’s DNA. Looking back on it, despite my feeling of imposter syndrome, Clay gave me a sense that I could do it and that we would succeed. That became a theme. Clay consistently saw things in me that I didn’t.

After Tom Vander Ark read an early manuscript of the book and offered some pointed pushback, Clay disappeared for a weekend and returned with two brand new chapters he had drafted by himself.

When McGraw-Hill published “Disrupting Class” in 2008, the education world was eager for Clay’s ideas and ready to learn from his teachings. Many education leaders knew he had been working on a book for some time. They were mostly a receptive audience, excited to read and, to be sure, debate his conclusions. After a decade dominated by talk of accountability in K–12 education reform, educators were desperate for a different way forward. They were hungry to innovate.

Beyond the precise prescriptions, “Disrupting Class” and Clay Christensen gave them a language to reframe the conversation. It showed how the existing education system had been successful—it delivered precisely the results it was built to deliver. Its faults were more the faults of a changing world, not of any individual or group within the system. To adapt, public schools would need innovation.

Although many have misread some of the points in the book in the years since—confusing concepts like disruptive innovation, for example, or thinking that we were writing predominantly about virtual schooling—thousands were inspired by its messages to transform, not reform, education; to mount a movement to create a student-centered education system by leveraging technology to personalize learning given that all students have different learning needs at different times; and to help all students fulfill their human potential. I’m still blown away by the numbers of people I meet who say reading the book caused them to teach or start an education company.

In my view, it was the right book at the right time by the right person. Although I’m thankful that I played a part in the movement, I also know that “Disrupting Class” and the Clayton Christensen Institute have had the impact they have because I stood on the shoulders of a giant of uncommon intellect, teaching ability and kindness.

And even as he passed from this earth last week, I, along with countless educators around the world, look forward to continuing to learn from the lessons of Clay to carry out the work about which he cared most: positively impacting the lives of individuals.