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Keeping a Lab Notebook

Keeping a useful and accurate lab notebook is a difficult but most useful skill to acquire. Evaluating a lab notebook is difficult and time-consuming. To improve the evaluation process so that it provides most useful feedback to students and to streamline the evaluation process for the professor, we have developed the following rubric.

  1. Motivation
  2. Figures
  3. Diary
  4. Data
  5. Analysis
  6. Summary


What is the purpose of the experiment? What physical principles are being explored or illustrated? What will be the difficult parts of the experiment? What are the main goals? A good Motivation section should answer these questions and lay the intellectual groundwork for the experiment to follow. This often includes a derivation of essential formulas or relations. You shoulddefine the symbols you use, often including a sketch illustrating the definitions.


There are two kinds of figures in a lab notebook. Sketches clarify a definition or illustrate a piece of equipment or how a measurement was performed. These should be schematic, focusing on the essential working principles involved, not on the cosmetic appearance of apparatus. Graphs display data in a visual format that should permit trends to be seen and a comparison between theory and data to be made. Graphs (including computer-generated graphs) should have proper labels and units, and data points typically should have error bars. Do not draw lines between data points. Lines or curves going through the data points should be labeled.


The lab notebook should detailed enough to be clear to you or someone else who wishes to duplicate your work at a later time. Do not underestimate how rapidly you forget experimental details. How was the equipment wired up? Does the distance recorded in my notebook include the radius of the ball? Is the "width" parameter in my book the distance between the edges of the slits orbetween their centers? Sketches and careful definition of quantities are essential to make the diary clear. When recording data, think carefully about the quantities you will need, and leave space to add more columns when you realize what you're missing.

Make your diary entries in chronological order on the right-hand page. Do not leave gaps to be filled in later. Use the facing left-hand page to add computer plots, error analysis, or other comments on the diary entries on the right-hand page. Date these supplementary entries.


Record your data neatly in tables, having carefully defined the quantities you record. Consider as you take and record data whether it is internally consistent, whether it agrees with the trends you expect; note any suspicious data points or events. Make a quick plot of the data if necessary to monitor the trend.


Here is the real guts of the report, where you tie together the theory and the data. Use your raw data to compute quantities you can compare to theory, including the uncertainties of the experimentally observed quantities and thevalues you calculate from them. Prepare a graph or graphs to illustrate the relationships you observed, and their agreement with theoretical predictions. Be sure to include error bars on plots.

Discuss the meaning of your data, including points of agreement and disagreement between your data and theory. Consider the measurement or measurements that limit the accuracy of your results and possible extensions to the experiment.


Summarize your report on no more than 1 page, describing succinctly what you did, what you observed (by referring to sketches, tables, and graphs prepared earlier in your book), and what it means. Avoid excessive use of "I" and "We".
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Copyright © 2001 Harvey Mudd College Physics Department
This page was last modified on Tue, Jan 13, 1998.