Sometime after discussing concrete and abstract nouns, and possibly even after discussing masculine and feminine nouns, the child can be introduced to collective nouns.
Invite the child to identify an object (have something prepared that you have several of) and briefly revise nouns and how everything has a name.
Then introduce the collection of items.
Some children may want to keep going with this work as they may enjoy matching the collective noun with the noun.
You can find my collective noun cards HERE and in list form HERE. You could use the list as the control of error (alternatively you can write the animal type on the reverse side of the animal card before laminating).
I think it is also important, either in the same lesson or in a follow up, to illustrate that collective nouns are not limited to animals (although they are often the more interesting examples). There are fleets of ships, bouquets of flowers, bunches of bananas and so forth. The children often have a lot of fun exploring the language of collective nouns and many will want to research more examples.
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