Writing Guidelines for Lab Report

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Overview

This document describes a general format for lab reports that you can adapt as needed. Lab reports are the most frequent kind of document written in engineering and can count for as much as 25% of a course yet little time or attention is devoted to how to write them well. Worse yet, each professor wants something a little different. Regardless of variations, however, the goal of lab reports remains the same: document your findings and communicate their significance. With that in mind, we can describe the report’s format and basic components. Knowing the pieces and purpose, you can adapt to the particular needs of a course or professor.

A good lab report does more than present data; it demonstrates the writer’s comprehension of the concepts behind the data. Merely recording the expected and observed results is not sufficient; you should also identify how and why differences occurred, explain how they affected your experiment, and show your understanding of the principles the experiment was designed to examine. Bear in mind that a format, however helpful, cannot replace clear thinking and organized writing. You still need to organize your ideas carefully and express them coherently.

Typical Components

  • Title Page
  • Abstract
  • Introduction
  • Methods and Materials (or Equipment)
  • Experimental Procedure
  • Results
  • Discussion
  • Conclusion
  • References
  • Appendices
  • Further Reading

1. The Title Page needs to contain the name of the experiment, the names of lab partners, and the date. Titles should be straightforward, informative, and less than ten words (i.e. Not “Lab #4” but “Lab #4: Sample Analysis using the Debye-Sherrer Method”).

2. The Abstract summarizes four essential aspects of the report: the purpose of the experiment (sometimes expressed as the purpose of the report), key findings, significance and major conclusions. The abstract often also includes a brief reference to theory or methodology. The information should clearly enable readers to decide whether they need to read your whole report. The abstract should be one paragraph of 100-200 words (the sample below is 191 words).

3. The introduction is more narrowly focussed than the abstract. It states the objective of the experiment and provides the reader with background to the experiment. State the topic of your report clearly and concisely, in one or two sentences:

Quick Intro Reference

Must Have:

  1. Purpose of the experiment
  2. Important background and/or theory

May include:

  1. Description of specialized equipment
  2. Justification of experiment’s importance

Example: The purpose of this experiment was to identify the specific element in a metal powder sample by determining its crystal structure and atomic radius. These were determined using the Debye-Sherrer (powder camera) method of X-ray diffraction.

A good introduction also provides whatever background theory, previous research, or formulas the reader needs to know. Usually, an instructor does not want you to repeat the lab manual, but to show your own comprehension of the problem. For example, the introduction that followed the example above might describe the Debye-Sherrer method, and explain that from the diffraction angles the crystal structure can be found by applying Bragg’s law. If the amount of introductory material seems to be a lot, consider adding subheadings such as: Theoretical Principles or Background.

Note on Verb Tense

Introductions often create difficulties for students who struggle with keeping verb tenses straight. These two points should help you navigate the introduction:

  • The experiment is already finished. Use the past tense when talking about the experiment.

    “The objective of the experiment was…”

  • The report, the theory and permanent equipment still exist; therefore, these get the present tense:

    “The purpose of this report is…”

    “Bragg’s Law for diffraction is …”

    “The scanning electron microscope produces micrographs …”

4. Methods and Materials (or Equipment) can usually be a simple list, but make sure it is accurate and complete. In some cases, you can simply direct the reader to a lab manual or standard procedure: “Equipment was set up as in CHE 276 manual.”

5. Experimental Procedure describes the process in chronological order. Using clear paragraph structure, explain all steps in the order they actually happened, not as they were supposed to happen. If your professor says you can simply state that you followed the procedure in the manual, be sure you still document occasions when you did not follow that exactly (e.g. “At step 4 we performed four repetitions instead of three, and ignored the data from the second repetition”). If you’ve done it right, another researcher should be able to duplicate your experiment.

6. Results are usually dominated by calculations, tables and figures; however, you still need to state all significant results explicitly in verbal form, for example:

Quick Results Reference

  1. Number and Title tables and graphs
  2. Use a sentence or two to draw attention to key points in tables or graphs
  3. Provide sample calculation only
  4. State key result in sentence form

Using the calculated lattice parameter gives, then,
R = 0.1244nm.

Graphics need to be clear, easily read, and well labeled (e.g. Figure 1: Input Frequency and Capacitor Value). An important strategy for making your results effective is to draw the reader’s attention to them with a sentence or two, so the reader has a focus when reading the graph.

In most cases, providing a sample calculation is sufficient in the report. Leave the remainder in an appendix. Likewise, your raw data can be placed in an appendix. Refer to appendices as necessary, pointing out trends and identifying special features.

7. Discussion is the most important part of your report, because here, you show that you understand the experiment beyond the simple level of completing it. Explain. Analyse. Interpret. Some people like to think of this as the “subjective” part of the report. By that, they mean this is what is not readily observable. This part of the lab focuses on a question of understanding “What is the significance or meaning of the results?” To answer this question, use both aspects of discussion: