Although your paper should have an introduction, never use a heading to indicate this point. A good title alerts the reader to the overarching theme of the work to be reported. A good title also captures the reader's attention. But the latter goal should not interfere with the former one. Never promise more than can be made good.
Abstracts provide a reader with the most important details.
Ideally, the abstract enables the reader to decide whether he or she should read the article. Again, never promise more than can be given. The abstract should not be composed of selected sentences from the body of the paper. Instead, the writer should sit down and try to distill the essential elements of the work to be reported. This portion of the laboratory report may not be required for your assignment.