No matter the hype, some technologies will either never take off in the classroom or may rapidly fade out after a strong start. But in their place, practical solutions make a difference.

You don’t have to travel far to find wild-eyed claims about the “next big thing in EdTech” (a quick Google search reveals dozens). But the fact of the matter is that many of the advancements once predicted to be “game changers” never ended up getting off the ground.

Of course, many of these technologies were great ideas, or worked well in neighboring industries. But the EdTech landscape is undeniably complex, and rarely do purportedly “revolutionary” technologies do more than attract a lot of publicity. And if they can’t justify their expense, they won’t justify universal adoption.

None of this is to say that the items on this list have had zero adoption — it’s just that adoption hasn’t gotten anywhere close to “viral,” or if it did, they may be facing rapid decline because of a number of reasons. It’s one thing if a few wealthy schools have adopted something or items were funded by “one-and-done” grants, but if 90% of school districts haven’t made it a priority, the transition hasn’t really taken off. One has to consider whether the ecosystem that supports adoption has started moving before taking a technology seriously. When colleges start teaching courses on how to use a given software, or when vendors start developing products around it, it’s fair to say that software has really “taken off.”

Here are three game changers that didn’t actually make a change.

1. Smart Boards

These interactive whiteboards project images and graphics onto an intuitive, touch-sensitive screen — providing for easy drawing, highlighting, and doodling over a variety of media. It’s a wonderful and highly-marketable idea, one that saw orders from 45% of U.S. schools in 2013. Today, however, the smart board market is in “terminal decline.” What happened?

For one, smart boards are complex and expensive; if any one part of four fails (display, computer, projector, or software), the whole system is out of commission. Second, teachers didn’t demonstrate a want or need for smart boards, so where they were foisted upon classrooms, they often went unused — a classic “cart before the horse” problem.

Finally, smartboards were the victims of bad timing. Just as the market started heating up, tablets and mobile devices butted in, offering a cheaper, more effective alternative. Few wasted time in making the switch.

2. Virtual or “Augmented” Reality

Virtual reality (VR) was predicted to revolutionize EdTech all the way back in 2012, but despite the fanfare it still generates today, VR has barely moved beyond the hype cycle.

While taking students on a, “virtual trip to Paris,” sounds thrilling, the fact is that VR headsets are quite costly. And while prices will lower over time, the larger issue is that the high-quality, VR-specific content that they require — VR’s “biggest cost” — isn’t exactly plentiful. Stitching together 360-degree videos shot from dozens of cameras is not amateur work. That leaves educators who want to customize their curriculums short on options, and short on interest.

One final nail in the coffin: VR makes many people incredibly nauseated and disoriented after even a short period of use. VR may have some niche uses, but by and large, it’s another cool idea whose time has come and gone.

3. Wearables

The sensor-enhanced digital devices called wearables have come the closest of these “game changers” to making significant impact — after all, they’re immensely popular in personal fitness and medical care.

Their promise is to track anything and everything in the classroom: student locations (GPS), health and activity levels (sensor-embedded clothing that measures heart rate and steps taken), classroom noise levels, individual pages read, and even student facial expressions. Then, presumably, that data is crunched to optimize the learning process.

Unfortunately, there’s little evidence that suggests any tangible benefit to students or teachers. Indeed, others have noted that creating such a “quantified student” could possibly be harmful: who interprets this data? How can educators create standards around its use? Given the lack of rigorous research, it’s hard to say. And, of course, the wearables with the best, most useful data are invariably the most expensive.

Few Products Prove Truly Indispensable

That last point is the most important. K-12 school districts and institutions generally have little in the way of excess funds, making investments in exploratory educational technologies exceedingly hard to justify. While each of these products is fascinating in theory, in practice, they haven’t delivered many meaningful results in day-to-day learning environments.

This isn’t to say that there aren’t any products worth the hype — there are many. For example, technologies such as cloud computing and mobile devices have proved to be truly indispensable, and will likely see even broader adoption in coming years. As “game changers,” they resolve two respective sets of demonstrated needs in a cost-effective way: the need to host a school’s online applications in a single place, and the need to grant students constant, hands-on digital access.

With every batch of new, hyped-up EdTech technologies, there are bound to be one or two that educators can’t ignore. However, a majority of these tools will never make their way over the hype horizon. The trick is to know the difference well in advance.