General to Specific

Turn the page to learn about the Drop Back Theory.

Have you ever wondered why some call numbers are so loooong?

The reason is, the more numbers you add,

the more specific the topic gets.

Let's say you want to do a report on dogs.

First, you go to the library and look in Applied Science (600).

As soon as you get there, there's one awfully big problem.

There are hundreds of books in the 600s.

So, let's narrow your topic. 

If you add a 3, (630), you get Agriculture and Related

Topics.  I know you're probably thinking, "what does that have to do with dogs?"

Well, that's ok, because it's about to make sense.

If you look in the 630s, you can find lots of books on

farming and farm animals, but the topic is still too general.

You could add a 5 and get 636.75 which is  Sporting dogs, hounds, and terriers and if you wanted to get even further information on  Sporting dogs, hounds or terriers all you do is add another number!  For example, if you wanted to find dachshunds, you go to hounds by adding a 3 which makes your number 636.753 and, like magic, you have a book all about dachshunds!

So, you add another number.  If you add a 6, the number is now 636, which is Domesticated Animals (animals that are tamed or not wild).  As you look at the books in 636, you discover your topic is still too broad, and you want to narrow it down some more.

636

The topic number for dogs is 636.7.   You could quit here because you only needed to do a report on dogs, but did you know that you could get even more specific than that?

ISN'T THAT NEAT!!!

Here's how to do it:   Our number now looks like this: 

Remember how we said every Dewey call number HAS to have 3 numbers to the left of the decimal point?  To make the topic even more specific, you'll have to add more numbers to the right of the decimal point.

Home

The 500s and 600s

500 - 600 Chart

General-to-Specific

Drop-Back

Theory

Let's "Dew"

It!