When Marina Bers and Mitch Rosenberg met at a 9-year-old’s birthday party in May 2011, they discussed a business idea, fittingly, for children. They arrived with their kids, who went to school together, and Bers buttonholed Rosenberg—who had a background in engineering and marketing—to discuss a prototype she was developing: A robotic toy that teaches problem-solving skills to 4- to 7-year-olds using computer science principles.

Bers, a child study and human development professor at Tufts University, wanted a startup veteran to help build her toy into a viable business. Rosenberg liked the product but wasn’t ready to leave his $190,000 paycheck. The following year, however, Amazon acquired Rosenberg’s company—a robotics manufacturer—and the payout on his equity stake was enough to let him forgo a salary, for a while at least, and take a risk.

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