The lab portion of a high school science course is designed to mimic the “scientific process”, and to get the most out of the lab and do well, students must have an understanding of what this process involves. In the most general terms, the scientific process begins with an observation of some phenomena and a hypothesis on why it occurs. Crucially, the hypothesis must be testable and stand up to experiment. Does the hypothesis hold water? The data collected during a well designed experiment, and the interpretation of that data, determines the validity of the hypothesis and if the hypothesis requires adjusting. When similar results are derived from multiple experiments, that hypothesis becomes a theory, and if it continues to hold up to further investigation it becomes a law. Observation, hypothesis, experimental design, data interpretation and further questioning outline the overall sequence, and high school science labs are designed to generate an appreciation for how this sequence flows. Support for material from that week’s lecture is of course relevant but a big purpose of the lab is to appreciate how theory taught in class derives from data generated during an experiment.
What then is the single most important factor for a student to consider when writing up a lab report? The hypothesis and experimental design are already taken care of, written by the textbook authors in the lab manual. Of course, students are asked to demonstrate a command of this in their pre-lab write-ups. But the single most important factor in a lab write-up is the accurate reporting of experimental data, and the student’s interpretation of that data. Students must record and report their data exactly as they observed it during their experiment, without attempt to report it as it “should have” appeared; that in fact constitutes fudging and we know where that will get us. Many students, when they see values skewed away from a known true value, will assume they have done something wrong and assume they will get penalized for it. They won’t; they just have to account for why the skew took place in their discussion of systematic/random error in the conclusion of their report. It is for this reason that many lab manuals have carbons in them! Students shouldn’t even rewrite their data from what they wrote down during lab; they should just turn in the sheets used to record their numbers and their observations, replete with nitric acid spills and bromophenol blue stains. The neatness and orderliness of the lab report is secondary, at least with regard to the data section.
Lastly students should do the write-up within hours of finishing the experiment, when they remember everything in greatest detail. In fact they should try and shoot for getting it done by the next day. This may not be a lot of days, but it is a lot of hours. While not so attainable if there is a Shakespeare exam at 8AM the next morning, finishing the lab report within a day of the experiment is the ideal, and doing so will of course get it out of the way quickly. There is also one less thing to worry about for quizzes and exams, as quizzes and exams tend not to ask specific questions about the lab. Remember, the lab reinforces the lecture material, and it is very unlikely that a test will have a specific question with regard to some particular lab procedure (this by the way is true for all science classes, even through college). So get them turned in, they will be easier to write and there is way less worry until the following week’s lab assignment!