Christian Varona didn't rely on textbooks and slideshows to learn history. When it came to studying for daunting Advanced Placement tests, he didn't turn to a tutor, either.

He just logged on to his computer and played some games.

"Ask my son how he passed AP courses in high school, and he will tell you it wasn't the teaching," said Christian's father, Juan Varona, a special education teacher in Miami. "It was historical games."

With many schools opening next week, there could be a lesson for others in Varona's success: Some computer games are a good use of time. Educators increasingly see digital games as a language that many students seem to intuitively understand, so they're trying to use that language to make playing facilitate learning.

This mindset has propelled popular mainstream games like World of Warcraft and Minecraft into classrooms in recent years as teachers craft curricula that have children engaged and playing. It has also pushed the development of other games designed to teach subjects such as math, vocabulary and AP history without relying solely on textbooks and pencils.

Game designers in Miami are even exploring possibilities outside the classroom by creating digital games that teach players about social issues - so-called "serious games." It's a small niche of the booming games industry that aspires to show that video games aren't all about first-person shooting, like in "Call of Duty," or sports simulations, like in the NFL Madden series.

Clay Ewing, an assistant professor at the University of Miami's School of Communications, creates serious games with his students. One example: a smartphone called "Zoo Rush" that explains to kids what it's like to live with sickle cell disease.

He said that besides the learning that comes with playing the game, his student designers learn the subject matter themselves. He found that students respond when you try to connect with them through gaming, he said, and teachers at all levels can capitalize on that.

"They're realizing that games are the cultural medium that the current generation responds to," he said. "For somebody who grew up on film and would say, 'Oh, I remember watching "E.T." in the theaters, and it was like a seminal moment in my life,' that same moment isn't going to be described in film. It's going to be talked about, like, 'I remember the first time my brother and I played "Super Mario Bros." It was transformative.'"

Educators are tapping into that connection. Results from a 2014 survey by researchers at the Sesame Workshop show that nearly 74 percent of teachers in a survey are using digital games for instruction. The center surveyed 694 K-8 teachers from across the United States in the fall of 2013.

Researchers continue to study the educational advantages of video games, and some of that work shows games can be a tool to increase student achievement. According to a 2013 study by nonprofit research institute SRI International that analyzed more than a decade's worth of existing research, using digital games in teaching can enhance student learning.

Some teachers have experimented with games like "World of Warcraft," a popular multiplayer online game. One middle school teacher in New York developed a way, with success, to teach "The Hobbit" using quests that correlate directly to Common Core standards.

Kurt Squire, a professor in digital media at the University of Wisconsin-Madison, said teachers who have designed lessons using games like World of Warcraft see students getting more excited about what they're learning.

This engagement means students not only dig into the topic at hand - they even work together on missions to achieve goals. The game becomes more than escapist fantasy. It takes problem-solving, collaboration and literacy to play well. And it challenges the idea that games are isolating and only lead to kids hunched over at a computer by themselves.

"They want to share strategy. They want to talk about what they're doing," said Squire. "I think that's the case, where reality defies some of our stereotypes."

UM's free smartphone app, developed with support from public health dollars, has a deceptively simple premise.

In "Zoo Rush," the player controls a cartoon zoo keeper in a brightly animated world where animals have escaped their cages. The character, who happens to have sickle cell, has to run after turtles, crocodiles and flamingos and shoot nets to capture them.

Along the way, the keeper has to make an occasional stop by the doctor to get medicine and it's also important to pick up bottles of water to stay hydrated. With the swipe of a finger, the player can avoid splotches of color that represent infections. After winning a stage, a player learns some basics about life with sickle cell from a screen with factoids about the disease.

Ewing said the goal for Zoo Rush was to provide a recently diagnosed child a positive way to deal with disease. That's the kind of impact Ewing, his fellow UM professor Lien Tran, and student developers hope to have with their serious games. Instead of handing out pamphlets at a doctor's office, they envision kids playing games to absorb vital information.

"It would be cool, if you had iPads, to put that on there," he said.

Although it might not be on the top of the charts in the application store on your smartphone, "Zoo Rush" has turned heads in the serious gaming world. It won the Silver Award from the 2014 International Serious Play Awards.

The possibilities are broad. Another social impact game Ewing helmed is Unsavory, where the player starts working at a taco restaurant and learns about the difficulties of working in the food service industry without getting paid sick days. Created in collaboration with nonprofit advocacy group Restaurant Opportunities Centers United, the game creates awareness of the challenges restaurant workers face. It's an economics lesson nestled in the shell of a video game.

But popular games have their place, too.

Amid the buzz of dozens of kids at an annual summer tech camp hosted at UM, an 11-year-old girl points, clicks and types her way through a digital world she's creating and a tale she's weaving on a laptop. Underneath her left arm lies a paper with the outline of a story she's written - the plot of the quest she's designing in "Minecraft."

"I really enjoy designing things, and I like to go on adventures," says Simran Vora, who came from Dubai to spend the summer with her grandparents in Miami.

She's taking her character on an adventure to recover a stolen piece of armor. The journey will take her through a world she's storyboarded and designed herself, complete with attacking pigs and jumps across several platforms and levels to eventually face off in a final battle where a giant pig stands between her and the armor.

In addition to using Minecraft to teach programming, organizers at iD Tech Camps, the national company that runs the camps at UM and other schools, have parlayed the game's potential into a teaching tool for game design, logic and storytelling.

"It's not just about playing the games. It's about customizing and making it what they love and what they want," said Maggie Harrell, director of Miami's iD Tech Camp. "At the same time, they're learning all these tools that will be so helpful to them in life."

"Minecraft" is a virtual building-block game where the player can build digital worlds with 3-D bricks. From an education perspective, it can be used as an alternative to using papier-mache and ice pop sticks to build a model - or even create staging an opera. That feat was described in a recently published book by USA Today's national education reporter Greg Toppo, "The Game Believes in You: How Digital Play Can Make Our Kids Smarter."

Toppo's book is an enthusiastic endorsement of using games to engage students in an academic world overly dominated by the drudgery of standardized testing.

"It offers kids the chance to create something no one has ever seen, something keyed to their passions but with an eye toward broadening them," he writes. "They start with one foot in a familiar world and end up somewhere new and different. In this case, of course, they're stepping from the digital world back in ours. Our gamers became students."

In Miami, the industry is growing, but a large portion of games are produced for entertainment. But one company, TurtleDiary, started a website in 2012 to host online math, reading and science games for elementary-age children.

"When they can learn it as part of a fun thing, they learn fast," said co-founder Permender Singh in a previous interview with the Miami Herald. "They don't even know that they're learning."

The interest continues to rise. The website has grown more than 30 percent during the last year, reporting the most popular grade levels are kindergarten, first and second grade. Currently, Miami-Dade schools that use the platform include Auburndale Elementary, Gilbert Porter Elementary and Jane S. Roberts K-8 Center. Their most popular games are math-based.

Parents in South Florida can be skeptical, but some are embracing digital learning and using games they find on their own to help their kids.

Jane Watkins, a travel and lifestyle publicist based in Miami, said her 9-year-old daughter has used phone applications like Duolingo for Spanish practice and Sushi Monster for math drills. She said she does limit the amount of time her daughter spends on games, but she credits them with making learning fun.

"While I don't credit the apps for her success, I do credit them with keeping her engaged and interested," she said.

Varona, the Miami teacher, has seen the success of gaming in his son's quest for high scores on an AP exams. In the classroom, he uses Oregon Trail, a history lesson woven through a decades-old computer game about 19th-century pioneers.

"In school, I try to introduce my students to games like Oregon Trail online," he said. "Taking part in history helps bring it to life."

In Miami-Dade, public schools offers students access to online learning applications and games during the summer through a program called iSummer: Learning On-the-Go.

Through the Student Portal on www.dadeschools.net, students from all grade levels can access Web-based programs that include district-licensed games, so kids can practice what they've learned at home or explore new material.

Edward Smith, principal of Miami Springs Senior High School, said the iTech Academy magnet program at Miami Springs is educating a new generation of who test their skills developing applications that entertain and educate. They also place an emphasis on how to market games in a fast-growing industry.

Smith, like so many educators, wants to meet students where they're comfortable - in a world loaded with mouse clicks and touchscreens.

"It's where these kids reside," he said. "It's how they learn, and how they can connect with people all around the world and share ideas."