💡 Quick answer:
→ If possible, use a plural noun + the 3rd person plural ⇒ help students with their homework.
💡 EXTENDED ANSWER:
A pronoun replaces a noun or noun phrase. The noun or noun phrase replaced is called the 'antecedent' of the pronoun, and the pronoun must agree in person and number with its antecedent.
➧El pronombre reemplaza al nombre. El nombre reemplazado es el 'antecedente' del pronombre, y ambos deben concordar en persona y número.
❓ Entonces, ¿cuál es el problema?
El problema es que, en inglés, la 3ra persona singular tiene 'he' (masculino), 'she' (femenino) e 'it' (animales + nombres inanimados).
Por lo tanto, cuando debemos reemplazar o referirnos a un nombre animado (persona) en singular que no distingue género (como 'a student', 'a child', 'somebody', 'everybody', 'a person', etc.), ¿deberíamos usar 'he' o 'she' o ambos?
HE/SHE: La primera respuesta puede ser que usemos ambos:
→ Everybody must do his or her best.
→ Someone has texted me; I don't know who he or she is.
THEY: Como solución, entonces, se ha comenzado a utilizar la 3ra persona plural (they) para incluir el femenino y el masculino:
→ Everybody must do their best.
→ Someone has texted me; I don't know who they are.
Esta opción no tiene aceptación unánime porque no hay concordancia en número entre el pronombre y su antecedente, y en contextos muy formales o académicos puede desaconsejarse. (See: Gender Neutral Language)
Sobre esta controversia, Oxford Dictionary dice:
"Some people object to the use of plural pronouns in this type of situation on the grounds that it’s ungrammatical. In fact, the use of plural pronouns to refer back to a singular subject isn’t new: it represents a revival of a practice dating from the 16th century. It’s increasingly common in current English and is now widely accepted both in speech and in writing."
🔗Go to full article ⇒ ‘He or she’ versus ‘they’.
🔗You can read more about the debate surrounding the use of ‘he or she’ versus ‘they’ on the Oxford Dictionaries blog.
Sobre este tema Cambridge English Grammar Today dice:
Traditionally, he and him were used to refer to both genders in formal writing:
If anyone has any evidence to oppose this view, let him inform the police immediately.
Nowadays, we often see gender neutral forms (e.g. he or she, he/she, s/he, (s)he, they and him or her, him/her, them) when we do not know if the person referred to is male or female:
The bank manager could help with your problem. He or she will probably be able to give you a loan. (or … he/she will probably be able to … or … they will probably be able to …)
Go to a hairdresser. Ask him or her to come up with a style that suits you, your hair, your lifestyle. (or … ask him/her to come up with a style … or … ask them to come up with a style …)
When you get into the building, go to the person on the desk in the reception area. They can tell you where to go. (or He or she can tell you where to go.)