Make tag questions of the following statements.

When the subject of a statement is an indefinite pronoun such as 'everyone', 'everybody', 'no one', 'nobody', 'someone', or 'somebody', the pronoun used in the tag question is 'they'.

The verb in the main statement, 'is', is positive. Therefore, the tag question must be negative. Since the pronoun in the tag is 'they', the auxiliary verb 'is' changes to 'are' in the tag question, becoming 'aren't'.

A tag question is a short question added to the end of a statement. It is used to confirm information or to invite the listener's agreement.

To form a tag question, you generally use an auxiliary verb (or 'be' verb) from the main statement and a pronoun that refers to the subject of the statement. If the main statement is positive, the tag question is negative. Conversely, if the main statement is negative, the tag question is positive.

In the given sentence, "The sweetest memories of childhood are colourful", the verb is "are" and the subject is "The sweetest memories of childhood," which is plural. Therefore, the pronoun 'they' is used. Since the statement is positive, the tag question is negative: "aren't they?"