A collective noun has many pieces inside of it, but the pieces are working together as one unit, so we write about a collective noun as if it is one thing.
We consider a collective noun to be a singular noun.
We usually use a singular verb with a collective noun.
A choir has many people in it, but when a choir does something, all the people in the choir do it together, so choir uses a singular verb.
The choir has been rehearsing all week.
Notice we said the choir has, not the choir have, because choir is a singular noun. We use a singular verb with choir.
Here are more examples of a collective noun with a singular verb:
Our group has planned a party for next Saturday.
Our Boy Scout troop is having a campout in May.
That swarm of bees is bothering me.
The herd of cattle looks impressive.
The deck of cards is on the table.
We also use a singular pronoun with a collective noun.
Team is a collective noun that has many people in it, but the team acts as one unit, so the collective noun team is a singular noun.
The team won its first game last night.
Notice that the team won its game, not their game, because team is one thing. We use a singular pronoun with team.
Here are more examples of a collective noun with a singular pronoun:
The gang painted its clubhouse black.
Our senior class chose its class song and class motto.
The crowd made its presence known by yelling and cheering.
The school band practiced its marching formation.
The committee has made its decision.
Whenever you use a collective noun in your writing, remember to use the collective noun as a singular noun. Use a singular verb and a singular pronoun with a collective noun.