As teachers, we need to help each other out.

Last week’s blog post was about teaching students when to use other, another, and the other. But confusion over these terms might not stop there. How do we form the possessive—is it each other’s or each others’? And should a singular or plural noun follow the possessive form? Should we use each other or one another? Get prepared for all these potential student questions by brushing up on the rules below.

Each Other’s or Each Others’?

This can be confusing for students, because the rule for possessives is usually ’s for singular count and non-count nouns and s’ for plural count nouns (e.g., one teacher’s desk, two teachers’ desks). However, you should point out to students that each other is treated as a singular pronoun and emphasizes two or more separate people. Each other’s is always correct, and each others’ is never correct. Think of it this way: You would say We talked to each other for hours. You would never say We talked to each others for hours.

• The students marked each other’s papers.
• They went to each other’s houses last weekend.

Singular or Plural Noun?

Since each other implies that two or more people are involved, the noun that follows is usually a plural noun (if it’s countable). Think of it this way: Let’s review each other’s essays means my essay and your essay; i.e., two essays.

• My roommate and I always borrow each other’s jackets because we’re the same size.
• We meet in each other’s offices when we need to discuss important issues.

Note that not all grammarians or style guides agree on this point. As a general rule of thumb, a plural noun is considered more common, while a singular noun is considered more logical. This would be great to discuss with higher-level students, but I wouldn’t recommend confusing lower-level students with it (stick with the rule above for lower levels).

• We borrowed each other’s jackets. (correct—more common—the two jackets were switched)
• We borrowed each other’s jacket. (correct—more logical—we each have one jacket)

Each Other or One Another?

The rule that grammar traditionalists follow is to use each other when there are only two people involved and one another for more than two. However, in my opinion, one another is quite formal, so each other can be used casually for more than two people. Also, I’ve heard people use one another for two people in formal situations, not just for more than two people. That’s why I teach my students to use each other no matter how many people are involved, but I do point out that they might see one another in formal writing or speaking.

• My best friend and I tell each other everything. (two people, casual, 100% correct)
• My best friend and I tell everything to one another. (two people, formal, generally accepted)
• As teachers, we need to help each other out. (many people, casual, generally accepted)
• As teachers, we need to help one another out. (many people, formal, 100% correct)

Source: The Chicago Manual of Style, 16th ed. section 5.220.