There's no denying that the iPad is the dominant tablet in the lucrative education market right now. Technology, however, is an ever-evolving beast--a field where all it sometimes takes to dethrone the king is the right platform, device or combination thereof at the right time.

Could other tablets soon cut into Apple's market share with help from outside marketplaces and learning platforms? Here are our picks for the top 10 tablets, marketplaces and platforms that threaten the iPad's dominance in the classroom:

1. GOOGLE PLAY FOR EDUCATION
With Android as the primary competition to Apple’s iOS, it was only a matter of time before Google better positioned its Chromebook and other Android tablets to against the iPad. With the recent reveal of Google Play for Education, it has done just that. The Android app and content marketplace allows teachers to search for peer-approved content by category, grade level and other criteria, and can even recommend content. NASA and PBS are already partnered as content providers, so time will tell how Apple responds to one of its biggest threats for classroom dominance.

2. DISCOVERY TECHBOOKS
Discovery’s line of digital textbooks are available on every device, adding one less reason for districts to stick to the iPad when planning out their tech budgets. The company has science techbooks available at the high school level in several disciplines, as well as K-8 science and middle school-level social studies, giving educators a variety of ways to engage students with interactive material on any platform.

3. NEWS CORP'S AMPLIFY TABLET
Media mogul Rupert Murdoch’s News Corp. made its own foray into the ed-tech marketplace with its acquisition of Amplify. The company’s Android tablets are designed specifically for education and are currently being used by an estimated 2,500 students at 12 schools nationwide. Despite losses, News Corp. is banking on the education space’s potential for growth to make the Amplify tablet a threat to the iPad’s dominance.

4. COURSESMART
An eTextbook platform, CourseSmart promises savings of as much as 60% off the price of print textbooks. Students can take notes, highlight text, copy and paste text, search within books, as well as access interactive eResources—links, homework, quizzes, videos and more. With its content from several publishers also available on less expenAndroid devices, CourseSmart is another platform that makes the iPad less of a classroom necessity.

5. SONY E-INK SLATE
At Japan’s Educational IT Solutions Expo, Sony displayed a 13.3-inch e-paper slate prototype co-developed with E-Ink. The tech giant plans to market the new e-reader device to students. It features stylus support, a flexible plastic E-Ink Mobius display, a thin and lightweight body, and 4GB of onboard storage plus microSD support and the ability to share notes via WiFi. However, it currently only supports PDF files and is likely to see some alterations and additions before being released later this year, so time will tell how it stands up to the competition.

6. MCGRAW-HILL SMARTBOOKS
You had to know the publishing giants would make their presence known beyond a single platform, and McGraw-Hill Education’s Smartbooks are no exception. The $19.99 reader-adaptive digital textbooks capable of measuring everything from retention to reading pace are available on Android tablets as well as the iPad. As of CES 2013 in January, they were also considering a Windows 8/RT version.

7. MACMILLAN DYNAMIC BOOKS
Like McGraw-Hill, Macmillan made the jump to the tablet space with its Dynamic Books. According to the Dynamic Books site, the e-textbooks capable of being customized, combined or rearranged are available on “other tablet devices” beyond the iPad.

8. CURRICULUM LOFT KUNO
In September 2012, ZDNet called Curriculum Loft’s Kuno tablet the iPad’s biggest competitor in the education market. The $375 Android tablet made by the spinoff of an obscure, 29-year-old, family-owned company in the Midwest has been deployed over the iPad by schools and entire districts in Texas, Virginia, Illinois, Iowa and Indiana. While it also plans to design a version of the Kuno specifically for healthcare and corporate users, the company plans to keep its David & Goliath story in education contained to the K-12 sector, stating that universities are “a very different market.”

9. KNO
Kno, which last year scored a rare cross-platform deal with publisher Houghton Mifflin Harcourt, allows parents of K-12 students to rent Common Core-rooted (but not state-specific) books for home studying for $10. The books include 3D features, links, notes and videos. Aside from the iPad, the etextbook platform is widely accessible via Android, Windows 7, Windows 8 and the Web.

10. BARNES & NOBLE, MICROSOFT AND PEARSON'S PARTNERSHIP
Last but not least, we have the recently announced partnership of Barnes & Noble, Microsoft and Pearson that the Wall Street Journal dubbed an “online education dream team.” Pearson gains 5% equity stake in Barnes & Noble’s NOOK Media with its $89.5 million investment, and Microsoft’s total investments of $300 million leave it with a 16.8% stake. Will this software, content and hardware powerhouse be enough to position NOOK tablets and e-readers as transformative educational tools capable of going toe to toe with the iPad’s foothold?

Would you like to see more education news like this in your inbox on a daily basis? Subscribe to our Education Dive email newsletter! You may also want to read Education Dive's look at 10 startups that are shaping the future of education.