Summarize this article in one sentence.
These and those are both pronouns, words that refer to or substitute for other nouns in the sentence. They draw attention to something specific. Because a pronoun takes the place of another noun, using the correct one helps your reader understand what the referent of the pronoun is (i.e., what noun it took the place of). These and those are plural pronouns: they refer to or replace plural nouns. "Agreement" means that the pronoun takes the same number as the noun it replaces. If the noun is singular, you would use this or that. If the noun is plural, you would use these or those. American English considers collective nouns, or nouns that refer to a large group of things that cannot be counted individually (such as milk or data), as singular nouns. Use this or that rather that these or those for collective nouns. For example: "This milk has spilled all over the floor!" British English differs from American English in using collective nouns. British English refers to some collective nouns such as crowd or data as plural, so it is appropriate to use these or those in British English. For example: "These data don't match the graphs you gave me." These is the plural form of this. You will use it to refer to or replace a plural noun. Singular: This book (a single book) on the shelf next to me belongs to Rajeev. Plural: These books (several books) on the shelf next to me belong to Rajeev. [Note that the verb belong has also been made to agree in number.] Singular: Look at this bracelet (a single bracelet) on my wrist! Plural: Look at these bracelets (many bracelets) on my wrist! Singular: Who put this cupcake (a single cupcake) in the refrigerator? Plural: Who put these cupcakes (some cupcakes) in the refrigerator? Those is the plural form of that. You will use it to refer to or replace a plural noun. Singular: That mountain (a mountain) looks really small from here. Plural: Those mountains (several mountains) look really small from here. [Note that the verb look has also been made to agree in number.] Singular: Could you hand me that box (a box) on the other side of the room? Plural: Could you hand me those boxes (a few boxes) on the other side of the room? Singular: Why hasn't that scientist (a scientist) at NASA found extraterrestrial life? Plural: Why haven't those scientists (many scientists) at NASA found extraterrestrial life? [Note that the verb have has also been made to agree in number.]
Understand the function of pronouns. Understand pronoun agreement. Understand the function of these. Understand the function of those.