Once upon a time, some thousands of years ago, there were no textbooks.
If one wanted or needed to learn something, the knowledge was gained by word of mouth. Storytelling was often used as a means of teaching.
Then about 2500 years ago, along came the Greek alphabet. For the first time, knowledge was accessible through the printed word.
But there were no means of mass-producing textbooks, or books of any kind for that matter.
All of that began to change in the 15th century when a German metalsmith by the name of Johannes Gutenberg invented the first printing press and cranked out the famous Gutenberg Bible in the 1450's.
For the first time in history, the mass production of printed material, including textbooks, was possible.
In America, the first textbook of historical significance, The New England Primer, was printed in Boston in 1690 and was used by students for more than 100 years. According to the University of Notre Dame's website, It combined the Bible with the study of the alphabet.
The website also points to a series of publications known as the McGuffey Readers. They were published from around 1841 to 1885.
"The readers were very moralistic in tone. They presented the White, Anglo-Saxon, Protestant as the model American.
These "eclectic readers" - meaning that the selections were chosen from a number of sources - were considered remarkably literary works and probably exerted a greater influence upon literary tastes in the United States more than any other book, excluding the Bible," according to Shannon Payne, writing for the University of Notre Dame.
Textbooks had become the main staple of America's education system.
Writing for the Atlantic Monthly in 2012, Megan Garber summed it up nicely: "Textbooks have remained, depending on your perspective, either amazingly consistent or amazingly stagnant over the thousands of years they've been around. Whether codexes or scrolls, whether scrawled on papyrus or printed on paper, their purpose has remained the same: to contain and systematize the educational experience, making knowledge both portable and economical."
Although electronic tablets and ebooks take up a good portion of the teaching pie these days, printed material still plays a key role in the education process.
And textbooks can be expensive.
At the college level, a year's worth of textbooks can be very pricey. But the cost has fallen quite a bit in recent years.
According to the National Association of College Stores, the average student spent $563 for materials in 2014-2015. That's down from $701 in 2007-2008.
But that doesn't mean all textbooks are becoming cheaper. A chart produced by the American Enterprise Institute shows the most expensive textbook at the University of Michigan is a chemistry book titled Principals of Instrumental Analysis. The price for a new copy: $400.65.
Back to tablets and ebooks. After the revolutionary electronic devices arrived on scene about five years ago, they were embraced by educators across the country.
Millions of students are now using them. The devices offer endless multimedia possibilities and can provide immediate feedback to teachers through the use of special apps.
Once you get past the initial cost of a tablet, software and Internet-based education sites become relatively inexpensive when compared to textbooks.
Experts believe the data from students' tablets will one day be harvested in order to personalize the learning experience. But for that to happen, leading educators believe there needs to be a 1 - 1 ratio in the classroom. Every student must have a tablet.
Many in the education field believe that will eventually happen.
Which means the days of printed textbooks in the classroom are likely numbered.