Why don't you see No. 1 or No. 3 pencils on your back-to-school checklist? Here's why the No. 2 is the Goldilocks of writing utensils.

No. 1 pencils were the darkest; No. 2 were the second darkest, and so on. Today, that scale includes 21 different grades, but No. 2 pencils are still the ultimate “tweener” pencil: ...

In all likelihood, if you rummaged through any given school desk in the U.S., the first pencil you'd encounter would be a number two pencil. Here's why. The United States tends to do its own thing ...

For the purposes of a test, a No. 1 pencil is a little too soft, and smudges easily; as you get higher in number, the lead becomes too dense and brittle to write and erase easily.