A collective plural is a group of items which are described as a single unit, such as a litter of kittens, or a platoon of troops. Learning to use collective plurals in speech is a bit tricky, because the collective plural can act together, or the individuals in the group may act separately, necessitating singular and plural verbs, pronouns, and so forth, respectively. Collective plurals are also used differently in different forms of English; for example, in Britain, it is common to see phrases like “the Parliament have passed a law,” treating the Parliament as a plural, whereas speakers of American English would probably say “the Parliament has passed a law,” treating the Parliament as a singular entity.
While a collective plural is often treated as a single thing, it is important to remember that a collective plural requires a group of individuals. A gaggle of geese, for example, requires at least two geese, and a murder of crows needs two or more crows. Collective plurals are sometimes referred to as “collective nouns,” and many common nouns have a collective form, like a bouquet of flowers, a stand of trees, and so forth.
When you use a collective plural, you need to decide if the members of the group are acting in concert, or if they are doing different things. For example, a goat herd springs collectively across a meadow as a group, but the individual members of the herd might split off to do different things, like go to their favorite napping spots. If the group is acting together, you should use singular verbs and pronouns, like “springs” above, treating it as a unit, while a group with members acting in different ways would need to be treated as a plural.
As you start thinking about how to use a collective plural in a sentence, it can sometimes help to play with the language you are using to determine whether the plural should be treated as a singular collective or a group of individuals. You can substitute a true plural noun for a collective plural, for example, to determine whether or not a sentence sounds strange, or you can add a clarifying term to a sentence to see if it still makes sense, using “jury members” instead of “jury” or “players” instead of “team”.
Agreement errors are common when people use a collective plural, and these errors are sometimes further confused by the lack of hard and fast rules which cause even professionals to slip up on occasion. Sometimes a sentence is technically correct, but it still sounds off, so people do not always strive for perfect agreement. However, you should be careful about doing this, because sometimes your decision to use something which sounds more comfortable can change the meaning of the sentence in a way you don't expect.