Descriptive Labs

InLab: the lab procedure

1. Setting up the lab:

Before you start the lab, review the objectives and the procedures you will follow. Take detailed notes as you gather your materials, set up your lab, and calibrate instruments. These notes will help you document your experimental protocol, which you can use later when writing the Methods section of your lab report.

  • List the materials you will be using. If using a specific instrument, you may want to make a sketch with appropriate labels for your lab notebook and for your lab report. If you have any questions about how to use any of the materials or equipment you will need for your lab, make sure to write them down. As you proceed with the lab, you will most likely find the answers. These notes will help you later when you write your lab report.
  • When using laboratory equipment, there are many sources of error or uncertainty that may arise. Make sure to note these in your lab notebook. You will need to refer to them again when you write your lab report.
  • In your lab notebook or manual, identify the types of data, you will be collecting during the lab, such as drawings, lists of physical properties, or descriptions of chemical reactions. Identifying types of data will make you ready to record your data properly in your lab notebook or manual.

Click here to see example lab notebook pages

2. Preparing to collect data:

If you are collecting quantitative data, identify the variables and units of measurement and create a table or set up a spreadsheet. If you are collecting qualitative data, determine the kinds of data you will be collecting and then prepare appropriate materials for recording observations (drawings, tables for observations, photographs, etc.). Read the lab manual to see what kinds of data you are being asked to record and be sure that you are ready to record the data in the appropriate form when you begin the lab procedure.

Whatever the data may be, it is very important that you organize them so that you can refer to them later on when writing your lab report. For help in determining which you should create now, a table or a spreadsheet, click here. For general information on tables, go to Designing Tables.

3. Collecting and recording lab data :

Carefully follow the experimental protocol. As you conduct your experiment and record your data, take notes on what you are doing and on any changes in the procedure. Taking good notes will help you recall the lab later on when you are writing your lab report. It's also important to note any problems with the procedure or deviations from the established protocol. Even if you are following the protocol in a lab manual, sometimes you will set up and run things differently. It could be that the materials specified in the lab manual were not available precisely as indicated, or perhaps your lab instructor decided to change the protocol somewhat.

As you record your data, you should be asking yourself various questions: What are the relationships among the variables? Do the data behave in the way that you had anticipated? If not, why not? If the data make no sense, you may need to consider sources of uncertainty once again. Sources of uncertainty may affect the accuracy and precision of your experimental data.

4. Visualizing the data:

If your data are quantitative, it may be useful to turn the table or spreadsheet you created into a graph. If you are going to keep your data in a table, revise the table so that it can be presented correctly in the report. Representing your data in the proper visual format will allow you to identify trends and relationships among variables more easily. For assistance with graphs or tables, follow these steps:

  • Establish what types of data you have, quantitative or qualitative.
  • Determine if the data should be represented as a table or a graph.
  • If you decide to use a graph to represent your data, determine which type of graph is one that best represents your data.
  • If a table is the best format for representing your data, then modify the table you used to collect your data so that it is labeled and organized properly. Go to Designing Tables for help on making tables.
  • If you need help creating a spreadsheet to make a table or graph, go to Excel Tutorial.
  • Remember that the purpose of your table or graph is to summarize your findings for yourself and for others and to reveal trends in your data.

5. Making sense of your data:

Review all your drawings, tables, graphs, and other data you collected during your lab and summarize in a sentence or two the overall finding for the lab. Then write a few sentences about how these findings help to answer the questions you raised in the PreLab, question 4. If you haven't completed the PreLab, you may want to go there now.

Summarizing your data in a sentence or two helps you to understand the lab. It is also useful for when you write the Results section of your lab report. Considering the questions from the PreLab will be useful for writing your Discussion.

If your lab instructor says it is OK, ask other students in the lab about their observations. Comparing your observations to those of other students can be valuable as a way of furthering your learning about the subject at hand. It is also a very common practice among scientists, which usually leads to more ideas and more laboratory investigation. It's OK if your findings are different. Your job is to try to figure out why, to identify the sources of the difference. You can use this information when explaining your findings in the Discussion section of your lab report.

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