In Russian, when you describe a noun, the adjectives have to match it.

This means the endings of the adjectives change based on three things:

1. The gender of the noun (is it masculine or feminine?).
2. The number of nouns (singular or plural).
3. The grammatical case (how it's used in the sentence).

Let’s explore this using the phrase "умные дети," which means "smart children."

Gender and Number

1. Identify the Noun:

   • The word "дети" means "children" and is plural. It comes from "ребёнок," which means "child" and is masculine. So, "дети" refers to both boys and girls.

2. Adjective Form:

   • The adjective "умные" means "smart" and is also plural, just like "дети."

Basic Adjective Endings

Here’s how adjectives change based on gender and number:

• Masculine singular: ends in -ый or -ий (like "умный")
• Feminine singular: ends in -ая (like "умная")
• Neuter singular: ends in -ое (like "умное")
• Plural (for any gender): ends in -ые or -ие (like "умные")

For "умные дети," we use "умные" because we are talking about more than one child.

Cases

In Russian, both nouns and adjectives change based on their case. Here are the cases you can use with "умные дети":

1. Nominative Case (who/what?):

   • Умные дети (smart children)

2. Accusative Case (whom/what?):

   • Я вижу умных детей. (I see smart children.)

3. Genitive Case (of whom/what?):

   • У меня нет умных детей. (I don’t have smart children.)

4. Dative Case (to whom/what?):

   • Я даю книги умным детям. (I give books to smart children.)

5. Instrumental Case (with whom/what?):

   • Я играю с умными детьми. (I play with smart children.)

6. Prepositional Case (about whom/what?):

   • Мы говорим об умных детях. (We talk about smart children.)

Practical Examples

Let’s look at some sentences using "умные дети":

• Nominative:

  • Умные дети играют на площадке. (Smart children are playing on the playground.)

• Accusative:

  • Я вижу умных детей, которые читают книги. (I see smart children reading books.)

• Genitive:

  • Он похвалил умных детей за их успехи. (He praised the smart children for their successes.)

• Dative:

  • Мы помогаем умным детям с их домашней работой. (We help smart children with their homework.)

• Instrumental:

  • Она разговаривает с умными детьми о науке. (She talks with smart children about science.)

• Prepositional:

  • Они пишут сочинения об умных детях. (They write essays about smart children.)

Conclusion

To sum it up, the phrase "умные дети" shows how adjectives must match nouns in number. By practicing different cases with this phrase, you can improve how you use adjectives in Russian. This will help you speak and write more clearly!