How to Do a Lab Write Up

Two Parts:Completing the Pre-Experiment Part of the Lab Write UpCompleting the Post-Experiment Part of the Lab Write Up

A lab write up is a clear, detailed outline of your experiment. It is used to describe and analyze the procedures followed and data collected. It contains many important elements, such as a hypothesis, materials lists, and raw data, and follows a specific format.

Part 1
Completing the Pre-Experiment Part of the Lab Write Up

  1. Image titled Do a Lab Write Up Step 1
    Choose a title. This is the name of the lab or experiment you are doing. The title should be descriptive, yet concise.[1]
    • Some teachers and/or classes require a title page. A title page includes the title of the lab or experiment, the name of the students completing the lab, the name of the instructor for whom the lab is being completed, and the date the experiment was completed.[2]
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    Determine the problem. Figure out what you are attempting to solve or test. This is the purpose of the experiment. Why are you doing this experiment? What will be learned from doing this experiment?[3] When you explain the purpose of the experiment, explain what the experiment will be about and what you want to determine.
    • This step should also introduce the experiment. Include background information relevant to the experiment, important definitions, theoretical and historical background, and general methods that are going to be used.[4]
    • The purpose should be stated in one sentence. It can be stated as a question. Sometimes, the instructor will give you the purpose of the experiment.[5]
    • An example of a purpose statement is: The purpose of this experiment is to determine the boiling points of different substances using three different samples.
    • An example of a purpose question is: Does red and blue paint mix to make green paint?
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    Determine the hypothesis. A hypothesis is the theoretical solution to the problem or predicted outcome to the test. Basically, the hypothesis is an educated guess of what you believe will be the outcome of the experiment. This is based on prior knowledge or experiments. You are not making up a solution with no support for it.[6] The hypothesis does not have to be correct. You are creating an experiment to see if it is supported or not supported.
    • The hypothesis should be stated in a sentence.
    • Use an "If this, then that, because of this" format for writing your hypothesis. Have "if this" be what you changed, "then this" be your result of the change. "Because of this" is why the reaction occurs.
    • An example of a hypothesis is: If I throw a ball from a fifteenth story balcony, it will make a crack in the sidewalk.
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    Make a list of materials. The next step is to write the materials used in a clear, concise list. Make sure to include all of the materials used. This will allow anyone to repeat your experiment and verify your claims.
    • Some instructors may let you refer to your textbook if the materials are listed there. This might look like: See page 456 in Chemistry Labs. Ask your instructor before doing this to make sure it is okay.[7]
    • Materials should be listed in a complete sentence. Write them in the sentence in the order that you used them.[8]
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    Explain your procedure. Write down the exact steps you followed during your experiment and the exact measurements you took. This takes you through a step by step procedure of the lab. Once again, this allows someone to replicate your experiment. Make sure to outline any precautions that should be taken when performing the experiment.
    • Detail all variables in the experiment. The controlled variables are the ones that don't change throughout the experiment. The independent variable is the one thing you will change during the experiment. It should be outlined in the hypothesis. The dependent variable is the variable that is changed because of your manipulation of the independent variable in the experiment.[9]
    • Some instructors require that the procedure be written in a paragraph form, not as a list and it should be a written description of what you did, not a set of instructions. Be sure to check with your instructor before writing this part of a lab report.[10]
    • The key to this step is clarity. You want to make sure to provide enough detail so that anyone can complete the experiment, and explain the steps in an easy to follow, detailed manner. However, be careful not to over explain or add in irrelevant information.
    • The procedure and materials list can be combined into one paragraph. Make sure to find out which way your instructor prefers before choosing.

Part 2
Completing the Post-Experiment Part of the Lab Write Up

  1. Image titled Do a Lab Write Up Step 6
    Perform the experiment. Using your procedures and materials, perform the experiment. You should complete all of the steps outlined in Part 1 before performing the experiment. Completing part of the lab write up before you do the experiment, such as the materials and procedure, is important because it gives you a clear idea of what will happen during the experiment. Writing out the hypothesis, purpose, and introduction material helps you understand the results of the experiment and not change your hypothesis based on the outcome of the experiment.[11]
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    Record the results. This section contains the raw data observed during the experiment. You should record your observations in clear, logical manner. Organize data and categorize the data so it is easy to read and understand.
    • This section includes data tables, graphs, or any notes made during the experiment. The data tables should be labeled clearly, and all units of measurement should be recorded. When using graphs, use X or O instead of dots. Make sure each axis is labeled with a variable.[12]
    • There are two different kinds of data that can be collected. Qualitative data is observable data that does not have a numerical value. These are things you observe with your five senses. Quantitative data is observable data that responds to measurable values. Examples of quantitative results are measurements in centimeters, weight in grams, speed in kilometers, along with density, volume, temperature, and mass.[13]
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    Discuss the results. In this section, analyze the experiment. Interpret the results by explaining them, analyzing what they mean, and comparing them.[14] If something unexpected happened, speculate as to why that happened. Hypothesize what might happen if a variable in the experiment was changed.[15]
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    Accept or reject your hypothesis. In the conclusion, explain if your hypothesis was correct or incorrect. Use data obtained from the experiment to support why you accept or reject it.[16]
    • Are there multiple conclusions that can be reached from the data? If so, make sure to say that. Explain what the other conclusions are.
    • An example of a hypothesis rejection is: Our hypothesis was incorrect. The cake did not cook at a higher temperature for a shorter amount of time. The cake was still raw when it was taken out of the oven.
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    Include any errors. Make sure to include any errors in your data, or data that is extreme and does not fit with the other data. Discuss reasons why the data might be wrong. State what you could do differently to improve the quality and preciseness of the experiment.


  • Ask your teacher for guidance if you are not sure what format to use.
  • Pick a lab that you know best and feel confident about. Then you can write more details.
  • Edit your paper twice, one for formatting, the other for content.
  • Use APA or MLA format, or whatever format specified by your instructor, for recording external data. Always cite your sources.
  • Most lab reports should be written in passive voice and in the third person. They should also be written in the present tense. Past tense can be used when describing specific methods and observations, or citing research or experiments done in the past.[17]
  • Never plagiarize your lab reports. This can result in failing grades or expulsion.

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