Lab notebooks serve as a permanent, chronological record of scientific work. Keeping a clear notebook is a key aspect of doing proper scientific research and you are thus expected to keep a scientific lab notebook throughout the semester. Lab notebooks serve several key functions for scientists:

1. They help organize your thoughts. The act of writing down what you are doing, why, the results and your interpretations of the results will help you better organize your thought process and ensure that you are thinking critically about your experiments as you do them.
2. They record your work so that you could come back to it later. Some scientific projects are continued for months, years or even decades and you may need to refer back to your notes to determine exactly how a specimen was prepared or to remember a certain protocol.
3. They record your work so that others could come back to or continue it later. Sometimes new people join projects – for example when an undergraduate joins a lab they may continue a previous student’s project. Thus you need careful (and legible) notebook entries so that others can study your work to continue or expand upon it. Students do not always realize that a lab notebook for work you do in a research lab does not actually belong to you – it belongs to the lab and must remain in the lab even after you complete your work.
4. They serve as a legal document. Lab notebooks are used in patent cases as legal evidence of who discovered/studied what and when.