THERE IS / THERE ARE

Examples:

Singular

There is a black cat.

There is a boy behind the tree.

There is a student in the classroom.

To make questions:

Is there a boy behind the tree? Is there a student in the classroom?

Plural

There are three football players.

There are two people and two dogs.

There are two little girls playing with blocks

To make questions:

Are there three football players? Are there two little girls playing with blocks?

There is used for information and facts. Sometimes "there" is singular, and sometimes "there" is plural.

Examples:

There is a clock on the wall. (singular)
There's a rabbit in the backyard. (singular)

There is = There's. Most Americans use the contraction, there's

There are seven days in a week. (plural).
There are some flowers on the table. (plural)

There are = (no contraction) Some Americans say "there's" even when the subject is plural. You shouldn't do that.