There is / There are and prepositions

In few words, you use it in this way:

• THERE IS: for singular ;  there's a chair;  there isn't much light here
• THERE ARE: for plural;  there are some pictures but there aren't any photos

This link is very useful to see this: click here

You can go to a previous entry to work with this grammar point  but there are some more  here:

• exercise 1     exercise 2      exercise 3

See you in class!