An abstract is a one page summary of your project. It should state your research question, purpose, and hypothesis. It should include you procedure, but you do not need to be as precise as you were in the procedure section; describe your steps more generally. Your results and conclusion should also be included. The abstract is meant to give a quick explanation of your project to someone before they start to read your paper and examine your display. Reference the science buddies web site for additional information.
http://www.sciencebuddies.org/science-fair-projects/project_abstract.shtml