An abstract is a summary of your project. It should state your research question, purpose, and hypothesis. It should include a summary of your 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