How to Keep a Useful and Organized Lab Notebook
Why Keep a Lab Notebook?
Lab notebooks are invaluable to scientists when they perform experiments. They are a combination of reference book, diary, and illustrated story that help scientists both remember what happened in the course of an experiment, and organize their data.
Think of a lab notebook as your own personal lab “cookbook.” Though we will be following a lab protocol (or “recipe”), each of us has our own flavor that we add to the experiment, and we record the things that we did, the observations that we made, and anything that went wrong that make the experiments uniquely our own.
A lab notebook has the following sections:
Purpose
What exactly am I trying to accomplish with this experiment? Why am I doing it? What techniques am I going to use? This section often contains a hypothesis, which is a statement of what you think the outcome of the experiment will be.
Materials
This is an exact list of the materials you used to complete the experiment, and is designed to make it is easy for you or someone else to duplicate the experiment. “Materials” include the identity and quantity of any chemicals you use, as well as glassware or instruments (like the balance). Be as accurate and specific as you can be!
Methods
What did you do? Note: This is not the same as what you were supposed to do. Record what you actually did. Did you make a mistake? Record it. Did you observe anything cool like a color change? Write it down—you may want to illustrate this section with a picture of the apparatus or use crayons or colored pencils to record colors that you observe.
Results
This is where your data goes. It is often useful to have a table here to help keep your data organized. All numbers that you record in your lab notebook should use the correct significant figuresand have units!!
Conclusions and Analysis of Error
In this section you interpret your results. What have we learned from the lab? Did we accomplish what we set out to? What are the things that cause uncertainty and error in the results? This is a good place to address anything you know went wrong during the experiment, as well as to hypothesize about other things that could be affecting your results.
General Rules for Good Lab Notebooks:
- ALWAYS record the units and use the correct number of significant figures
- Include an up-to-date table of contents with the name, page number and date of each experiment. It is also helpful to date and number each page.
- Keep your lab notebook as neat as possible by using the left-hand side of the page for scratch-work and having the right-hand side be the “good” side—a continuous story that is legible.
- Use pen and don’t erase! If you mess up just draw a line through it and move on—in science, it is always useful to be able to see our past mistakes.
EXAMPLE: Baking Chocolate Chip Cookies
Purpose: The purpose of this experiment is to make delicious chocolate chip cookies using ingredients I have in my kitchen, standard kitchen appliances and an oven. Hypothesis: By combining the ingredients and baking them, I will have chocolate chip cookies.
Materials: Here, I would list all the ingredients I used (eggs, flour, sugar, etc.) as well as the tools I used (a bowl, a mixer, a cookie sheet, my oven).
Methods: This is the cooking process—I would describe everything I did, including mixing, taste-testing, forming the cookies, cooking them and letting them cool. I’m not just reciting the recipe, but saying what I actually did.
Results: I have 26 chocolate chip cookies. Upon being tasted, they are, in fact, delicious.
Conclusions and Error Analysis: From this experiment, I would conclude that chocolate chip cookies can be made using ingredients and tools that I have in my kitchen. In my error analysis, I would discuss what kinds of things happened that may have affected the outcome (did I not stir the dough together enough? Did I not have enough flour so I cheated a little?). Did something unexpected happen—e.g. are my cookies burnt? If so, I would discuss what might have led to that. Also, I should discuss ideas for future experiments—what could be done to improve this cookie recipe? What are some of the limitations of cookie recipes in general?