Topic is too broad

You will have too much information to go through
You will not have enough time to read everything
You will have too many issues to cover effectively
Your assignment may lack depth

How can I narrow my topic?

Find a focus by selecting a specific issue of interest
If possible, choose a geographical location or time period
Consult a subject encyclopedia to learn more about specific issues

Example

You have decided that your topic will be immigration to America. If you start searching for information with a topic that is too broad, you will end up with way too much material. Your best bet is to find a focus.

Here are a few examples:

Choose a place of origin and a time period: Irish immigrants in America in the 19th century
Select a specific issue or effect of immigration: The cultural effects of Ukrainian immigration in the western United States
Select a topic that reflects a current situation: Multiculturalism in large urban cities (if you find too much information, you could select a city to focus it even more)