The FCAT is a test that is given to Florida students to rate their performance nationwide. If you child goes to school in the state of Florida they will have to take this test and there are many ways to help prepare them. The first and most important is to make sure they go to school regularly and talk about the progress of your child with their teacher. At home, make sure they have a quite place to study and that they are well rested before test days.
For more information on the FCAT and how to prepare:
http://fcat.fldoe.org/aboutfcat/english/about.html