Possessive Adjectives: They are either singular or plural and must agree in number with the nouns that they describe. 
Singular Possessives

Mi-my                                  Nuestro/a-our

Tu-your (Familiar)             Vuestro/a-your

Su-your                              Su-your

Su-his, her, its                   Su-their

1. Mi casa es su casa.(My house is your house).

2. Tu libro esta en la mesa.( Your book is on the table).

3. Su pluma es roja  (Your pen is red).

4. Su pelo es rojo y azul. (His, her, its hair is red and blue.)

5. Nuestra maestra es inteligente. (Our teacher is intelligent.)

6. Vuestro (Spain) estudiante es Argentina.(Our student is Argentine.)

7. Su perro esta simpatico. (Their dog is nice.)  
Plural Possessives

Mis-my                      Nuestros/as-our

Tus-your                    Vuestros/as-your

Sus-your                    Sus-your

Sus, his, her, its        Sus-their          

1. Mis casas son sus casas.

2. Tus libros estan en la mesa.

3. Sus plumas son rojas.

4. Sus pelos son rojos y azules.

5. Nuestras maestras son inteligentes.

6. Vuestros estudiantes son Argentinos.

7. Sus perros estan simpaaticos.
Special Note: In order to clarify possessive adjectives for su, which could refer to his, her, or its, remember to use (de el, de ella, or de usted).

1. Su casa es mas alta que tuya.( La casa de el es mas alta que tuya). His house is taller que yours.

2. Su  casa es mas alta que tuya. ( La casa de ella es alta que tuya).Her house is taller que yours.

3. Su casa es mas alta que tuya. La casa de usted es mas alta). Your house is taller than yours.    

4. Es la tia de nuestros/as. She is our aunt.
                   de vuestros/as  She is your aunt.
                   de ustedes
.
Translate each statement using the correct possessive adjectives.

1. It notebooks.is his book. _____________________________________.

2. It is her pen. ____________________________________________.

3. It is your homework. ______________________________.

4. They are his books. ______________________________________.

5. They are her pens. _______________________________.

6. They are your homework. _________________________________.

7. It is my car. _____________________________.

8. They are my. _________________________________. 

9. She is our sister. ________________________________.

10. He is our cousin. _________________________________.

11. We are their cousins. _____________________________.

12. He is my teacher. ________________________________.

13. They are my students. _____________________________.

14. It is her dress. _______________________________.

15. They are his pants. ________________________________.

16. Our class es in the cafeteria. ______________________________.

17. Your friends are good. ____________________________________.

18. He is my uncle.________________________________________. 

19. My chairs are yellow. __________________________________.

20. His desks are blue. ___________________________________.