Nouns ending in a consonant followed by -y change the -y to -ies in the plural form.
Activity is regular. It follows the -ies Conversion rule.
Use plural verbs: "The activities are ready" (not "is ready").
Yes. The plural activities is standard across all English variants.
The word activity follows the standard English pluralization rule. When forming the plural, activity becomes activities. This follows the -ies Conversion pattern, which is one of the most common plural rules in English.
Understanding why activity becomes activities helps with spelling and pronunciation. Nouns ending in a consonant followed by -y change the -y to -ies in the plural form.
When using activities in writing, remember that it functions as a plural noun in sentences. It pairs with plural verbs and pronouns. For example: "The activities are ready" (not "is ready"). This subject-verb agreement is essential for grammatical correctness.