There are many different types of lined notebook paper, and each one goes by a different name—college ruled among them. To help tell them apart, you might have to break out a ruler.

Before we proceed any further, some historical context is in order. Paper that’s printed with evenly-spaced horizontal lines across its surface is called “ruled” paper. For centuries, these lines had to be drawn by hand. But in 1770, the game changed. In June of that year, inventor John Tetlow patented a device that the British government described as a “machine for ruling paper for music and other purposes.” Incidentally, Tetlow named the contraption after himself.

Since then, ruled paper has evolved quite a bit. Here in North America, manufacturers recognize three main varieties:

The first of these is called wide ruled paper, which comes with large gaps between the individual lines. In general, these blank divides are 11/32nds of an inch (approximately 8.7 millimeters) across or wider.

Next, we’ve got medium ruled—or “college ruled”—paper. Sheets of this type have slightly smaller interline gaps of only 9/32nds of an inch (7.1 millimeters).

Finally, there are the aptly named narrow ruled sheets. If you have a hard time reading tiny letters, this sort of stationery isn’t for you. A meager 8/32nds of an inch (.25 inches or 6.35 millimeters) or fewer separate the lines on narrow-ruled paper.

By and large, wide ruled paper is the preferred choice of elementary school teachers. It’s an especially common sight in kindergarten, first, second, and third grade classrooms. The reason for this is simple enough: Little kids who are just learning how to spell their names usually scrawl it in very large letters, so they require paper that has a lot of space between the lines. 

“College ruled” paper is so named because it’s what older students generally use. As children grow up, they’re able to write smaller letters, numbers, and symbols. Hence, most of them will have graduated from wide ruled to medium ruled sheets by the time they enter high school. And at most institutions of higher learning, notebooks with medium ruled paper are omnipresent—although plenty of college students remain wide ruled fans. To each their own.