Dear A:

You wrote:

>Hello,
>I’ve heard that it is incorrect for someone to say: “John and I worked on the project.” Is this true? If so, why? I’ve heard that proper or grammatically correct way to make such a statement, would be the following: “Me and John worked on the project” or “John and me worked on the project.”
Your assistance and clarification would be greatly appreciated.
>Thank you,

The grammatical way is just the opposite. I is for subjects. Me is for objects. Try the sentence without the extra noun in the subject. Is it “Me worked on the project” or “I worked on the project”? Clearly, the correct way is “I worked on the project.” The same pattern applies if the subject is compound. “John and I worked on the project” is correct.

We normally put I last in any compound subject out of politeness. In other words “John and I” is preferred over “I and John” because it is polite to put others before ourselves.

For more on this, see Grammar Slammer “Pronoun Case” or https://www.englishplus.com/grammar/00000021.htm.