Today's English lesson

From the American Heritage Book of English Usage:

To Each...

each with singular or plural verb.

The traditional rule holds that the subject of a sentence beginning with each is grammatically singular, and the verb and following pronouns must be singular. Thus you should say

Each of the apartments has (not have) its (not their) own private entrance (not entrances).

When each follows a plural subject, however, the verb and subsequent pronouns remain in the plural:

The apartments each have their own private entrances (not has its own private entrance).

But when each follows the verb with we as its subject, the rule has an exception. You can say either

We boys have each our own room.

or

We boys have each his own room.

though the latter form may strike readers as stilted.

each and every.
The expression each and every is likewise followed by a singular verb and singular pronoun in formal style:

Each and every driver knows (not know) what his or her (not their) job is to be.