In his 2015 book, "The End of College: Creating the Future of Learning and the University of Everywhere," author Kevin Carey distills a brave new world in which a myriad of lower-cost solutions--most in their infancy--threaten to upend the four-year, high-tuition business model by which colleges and universities have traditionally thrived.

Back in April, when his book came out, I listed 16 of the startups providing those solutions. Now that it's back-to-school season, the time is ideal to revisit the topic, with an eye on companies whose offerings can potentially upend September's classic rituals: brick-and-mortar shopping for supplies, cross-country drives to bucolic settings, sleeping on well-worn futons. Without further preface, here's a list of seven startups (sourced from Carey's work and elsewhere) poised to forever change the essence of back-to-school week.

1. The Minerva Project. 

Most startups hoping to disrupt the $4.6 trillion market for global education sell their services to traditional schools or directly to the students themselves. The Minerva Project is, literally, selling a new school.

It promises a world-class undergrad education for $10,000 in annual tuition. It relies on online teaching methods and saving costs by avoiding the expenses of athletics programs, labs, and libraries. Yet the students live together in a small urban setting and enjoy a community experience. As freshmen, they live in San Francisco. They then spend each of the next six semesters together in a different global city. 

The first class of 28 students finished its freshman year in April. This September, 113 students will enroll, according to the San Francisco Chronicle. Whether Minerva will succeed, only time will tell. Regardless, Minerva is betting big on a novel approach to the undergrad experience. 

2. CampusTVs.

CampusTVs rents large flatscreens to college students for the school year. Talk about an easy-to-explain concept. In its first year, 2013, the company was on 50 campuses. Last year, the company expanded to 300 college and university campuses.

But wait, there's more: In an impressive early pivot, the company recently launched a division called Campus SIMs, which lets international students use their mobile phones in the U.S. So far, 125 schools have signed up, according to BostonInno. By broadly defining its business model around students' high-tech pain points, CampusTVs is making a significant difference in how undergrads adjust to life on campus. 

3. Wigo. 

Last September, this app launched and within weeks was in use at 73 schools with more than 100,000 active users. The app helps students find out "who is going out" (thus: W.I.G.O.) on a given night. Before the school year was over, Wigo had amassed more than 50,000 registered users at more than 1,300 schools.

A USA Today headline asked, "Is Wigo revolutionizing the way college students socialize?" It's too early to say for sure. But if your one-year-old app is provoking those kinds of questions, you belong on this list. 

4. Course Hero.

One of Inc.'s 30-Under-30 companies from 2013, Course Hero is an online source of study guides, class notes, past exams, flash cards, and tutoring services. More than five million students use its resources.

Though it's hardly a startup anymore--it was founded in 2006--it's still receiving rounds of VC money (including a $15 million infusion late last year).

5. Quizlet. 

This is another site offering shared learning tools from students worldwide. Available in 18 languages, Quizlet boasts a consistent showing in the top 10 free education apps in the iTunes and Google Play stores.

6. Rafter.

Using cloud-based e-textbooks and course materials, Rafter helps campus bookstores digitize their offerings and keep their prices low, allowing them to regain the market share they were losing to other stores and course-materials marketplaces.

The school wins because store revenues rise. The students win because course materials are cheaper. All of which means, Rafter wins too.

7. Casper.

Time was, you slept on a used futon you found on a street corner, or that was left in the room by the previous semester's inhabitants. That time is over, thanks to Casper and a cavalcade of other online mattress retailers who've launched in the last few years.

These startups are raking it in: Casper, Tuft and Needle, and Leesa are each selling more than $1 million in mattresses a month. Saatva posted $29 million in 2014 sales and expects at least $50 million this year. More to the point, these startups are changing the sleeping experience of the average off-campus dweller.