Descriptive Labs

SECTION THREE : Introduction

Establishing a context for the lab

Step 1: Begin the opening paragraph of the Introduction by stating the scientific concept (principle, theory, law) or laboratory procedure of the lab. Then finish the paragraph by writing down all the details about the concept or procedure relevant to the lab that you can find in the lab manual, textbook, class notes, handouts, etc. If you completed the PreLab, this step corresponds to question 1. Note any citations you use here for including in the References section of your report.

More Help:

  • If you are having trouble writing a good opening sentence for the lab report, you can say something like: "This laboratory experiment focuses on X…"; "This laboratory experiment is about X…" ; "This lab is designed to help students learn about, observe, or investigate, X…." Or if you are working with a scientific concept or procedure, you can begin by defining it: "X is a theory that…"; or "X is a procedure that is used for..."
  • Once you have your opening sentence, you are ready to complete the opening paragraph by telling what you know about the scientific concept or lab procedure. The point is to show your lab instructor that you have a good grasp of the scientific concept. Make sure to include the following:
    • Information about the scienctific concept or laboratory procedure that is directly related to the lab (not everything there is to know about the concept or procedure)
    • Additional relevant information about the concept or procedure you may have learned since doing the PreLab or since doing the lab.
  • If you have a lot to say about the scientific concept or lab procedure, use more than one paragraph.
  • This part of the Introduction is typically written in present tense.
  • For help with citing references, go to Citations and References.

For more advanced labs:

If you are writing a lab report that is more like a full scientific paper, you may need to do more research using the internet and library. With your teacher's guidance, you should search the recent scientific literature to find other research in this area of study. Summarize that research in a paragraph or so, stating what the general findings have been and using those findings to describe the current knowledge in the area (such a "review of the literature" is typical of scientific journal articles). This summary should come after your initial sentence about the scientific concept. For help with citing references, go to Citations and References.

Step 2: Write in sentence form the objectives for this lab--specific things you are being asked to do in the lab, such as measure, analyze, observe, test something, etc. Then, continue the paragraph by describing the purpose of the lab--how the achievement of these objectives are designed to help you learn about the scientific concept or procedure of the lab. If you completed the PreLab, this step corresponds to questions 2 and 3.

More Help:

  • Objectives are typically actions you are being asked to perform for the lab. Often the objectives are listed in the lab manual. Writing the objectives of the lab in your own words demonstrates your understanding of what you were supposed to accomplish in the lab. With most labs, you should be able to do this in 1 or 2 sentences. You can begin by saying something like: "The main objectives of this lab were to…"; "In this lab we were asked to…." This will be the beginning of the paragraph. If your response to PreLab question 2 was a list of objectives, revise it by summarizing the primary objectives in your own words.
  • Continue the paragraph by addressing the purpose of the lab. This is where you make the all-important link between what you do in the lab (the objectives) and the purpose for doing the lab: to learn something about the scientific concept or procedure of the lab. Read over the objectives again. In what way do you think that doing the experiment, accomplishing the objectives, helped you learn about the scientific concept? You can start by saying something like this: "The objectives of this lab enabled me to learn about X by…"; "Performing these objectives helped me to understand X by…." If you completed the PreLab, revise question 3, showing that you comprehend the purpose of the lab.
  • This part of the Introduction is usually all in past tense.


Step 3: Describe the questions you had before doing the lab, things you didn't understand or would like to know more about. These are questions about the scientific concept, lab materials, procedures, or application of this lab to other scenarios. If other questions came up as you were completing the lab, include them here as well. State why these questions are important to understanding the lab. Make sure to describe your questions in the context of the scientific concept for the lab. If you completed the PreLab, this step corresponds to question 4.

More Help:

  • Since the purpose of the lab and the report is to help you learn something about science, the final paragraph of the Introduction should create a learning context for the rest of the lab report. Writing a paragraph that describes issues that you didn’t understand or wanted to know more about before or during the lab establishes a basis for learning. It shows what you may be able to learn by doing the lab. You will return to these issues in the Discussion.
  • If you did not do the PreLab, one strategy for finding these issues at this point is to go back to the lab manual and read the section about this lab. Look for things that you were unclear about before you did the lab. Perhaps, you didn’t fully understand aspects of the scientific concept for the lab. Or perhaps there were some details about how to perform the lab procedure that were not clear to you. It may be that you were curious about how you could apply the lab protocol to another situation. You can include issues that you still don’t understand.
  • To write the paragraph, describe what you don’t know or are just curious about. You can do this in sentence form or list them in bullets.
  • To show how the issues you raise are important to the lab, show how they relate to the main scientific concept or procedure of the lab.



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