It’s Monday morning, and the president of Back Bay Battery, a $240 million company, is looking over his financial statements. Sales are way up for his main line of nickel metal-hydride batteries, and yet he can’t help noticing the customer complaints, particularly about how long the batteries take to recharge.

The company’s new ultracapacitor batteries recharge in less than a 10th of the time, but so far they’re losing millions of dollars as the company scales up production. Betting that they’re the future, though, Back Bay’s president takes a deep breath and decides to shift scarce R&D dollars away from nickel metal-hydride research and toward ultracapacitors.

It might sound like another stressful day at the office, but it’s actually a stressful day at school—the business simulation will be part of an assignment for Harvard Business School students in their second-year Building and Sustaining a Successful Enterprise course.

Simulations like Back Bay Battery have become increasingly popular at business schools as educators seek to promote experiential learning over passive instruction via lectures, arguing that students work harder and retain more information when given more hands-on instruction. And they seem to be a natural fit for students raised on playing videogames. Today more than 90 percent of business schools use at least one simulation in their teaching, and many use more.

Simulation games have become so successful that H.B.S.’s publishing arm, Harvard Business Publishing, which also produces the classic case studies that generations of B-school students were weaned on, has begun producing its own simulations in partnership with Forio Business Simulations. One of the first is a simulation of running a Benihana restaurant that’s based on a bestselling case study. Other simulations focus on specific business situations and challenges, such as managing a complex supply chain (The Root Beer Game), running a technology-driven business (Back Bay Battery), and climbing Mount Everest as part of a team (Everest).

“Experiential learning is a big deal everywhere” says Denis Saulnier, Harvard Business Publishing’s assistant director for educational technology. “[We] saw it as a natural complement to the case-study method," he says, adding that students actually get to act out scenarios and see cause and effect.

Saulnier says that while sales of its simulations and other e-learning products are nowhere near that of the publisher’s paper cases because they’re so new, they are the fastest-growing part of its catalog, and he expects them to become a significant part of overall sales in the future. Customers of the simulations, which typically cost about $12.50 per student, include many of the country’s top business schools, including Columbia, Cornell, and Carnegie Mellon.

Harvard Business Publishing already has some strong competition, however. Dan Smith, president of Capsim Management Simulations, estimates that sales of his recently launched Comp-XM game, in which students run a virtual $100 million company for five sped-up years and answer questions about their decisions, are up 20 percent over last year. And Sam Wood, a former Stanford Business School professor who founded Responsive Learning Technologies to market the games he and fellow professor Sunil Kumar developed, notes that the majority of schools accredited by the Association to Advance Collegiate Schools of Business now use either his or Capsim’s products.