Hillary Clinton and Donald Trump skipped over one big issue during Monday’s debate: productivity.

At least that’s according to Rana Foroohar, assistant managing editor at TIME. In an exclusive interview with Fortune, Foroohar, who is also the author of the book Makers and Takers: The Rise of Finance and the Fall of American Business, says that productivity in the United States is down. And she believes this has slowed economic growth.

While productivity is one of the most important metrics in measuring how well the economy is doing, according to Foroohar, the issue isn’t exactly black and white.

“Neither candidate wants to get into this because it’s complicated and wonky, and because there’s not as much the presidents can do about this,” she says. “It’s not like talking about tax policy, or trade—it’s really a deeper issue.”

But Foroohar thinks furthering education is the solution to increasing worker and economic productivity, especially as more technological advancements are made.

“There’s a lot of research to show that as long as education can stay ahead of technology, workers can become more productive,” she says. “If you can bolster education, and if you can boost infrastructure and tie that to worker training, that would be a good thing for productivity.”

To further her explanation, Foroohar uses automated cars as an example: Since the leading occupation for working class men right now is driving, she says, automated cars will eventually take those jobs away.

“People will need to have new skills to boost the economy,” she says.

For their full conversation, watch the video above.