A student surrounded by laboratory equipment

So, what goes in the procedure section?

Information in the procedure section can be classified in one of two categories: information about the equipment and information about the experimental procedure.

You might want to include a detailed description of your equipment before explaining the experimental procedure, or you may want to integrate this information. In some situations, it may be acceptable to write the experimental procedure as a numbered list. However, it is usual to write prose.

The general rule is that information should be presented in a logical order so that each statement follows on from the previous one; your reader should never have to look ahead to understand a statement.

The amount of information and detail you include will ultimately depend on the length of the report, and importantly, the extent to which you use experimental diagrams.

A well-labelled schematic diagram can help you to clearly explain the experiment whilst reducing the amount of text. Ideally, you should produce the diagram first, and then the procedure is easier to write.

Let’s start with the first category: equipment.

What equipment did you use?

When it comes to describing your equipment, you may find it useful to consider the different types of equipment you used. All equipment falls into one of four categories:

  1. Measurement equipment: The equipment you used to record your results. This could be in analogue form or a digital display.

  2. Facilitation equipment: The core of any experiment. This is the ‘action’ equipment which allows ‘changes’ to be made to the system such as heaters, pumps and electrical power supplies.

  3. Auxiliary equipment: This is equipment that is helpful, although not strictly necessary for the experiment. This might include stands, receptacles and working surfaces.

  4. Composite equipment: This equipment combines the first and second categories, much of the proprietary teaching equipment that you use will fall into this category.

Report the operating state of your equipment

You should note the operating state of equipment that has an on/off button. Such equipment can be considered to have one of the three following operating modes:

  • Off (not yet switched on)
  • At steady-state (on, and with all operating parameters staying constant with time)
  • Unsteady-state (with one or more parameters changing with time)

Example: Consider a heater. Once the heat is switched on, it will take some time to reach steady-state, at which the temperature will be constant.

For some equipment, the time taken to reach steady-state is instantaneous, but for other equipment, the time is significant and should be made clear in the procedure. Also, at the end of the experiment, it should be made clear whether the equipment is switched off after the experiment or left operating.

Listing the make and model

If the procedure can only be repeated using a particular piece of equipment, or the result would be different if a different manufacturer’s equipment were used, then the details of the make and model number of the equipment should be included. Otherwise, there is no need to include this information in the description.

There can be ethical considerations when describing the equipment you used. For example, mentioning equipment manufacturers by name could be regarded as inappropriate advertising, especially if there are alternative models.

This can be compounded by expressing opinions on the operational performance of the equipment - especially when the results are being discussed.

Example: The results from the voltmeter were questionable due to a poor standard of construction and an inability to obtain a stable reading, a feature available on models of similar equipment from alternative manufacturers.

To avoid controversy, be sure to express these types of opinions in dispassionate and objective language.

Example: The equipment was switched on and voltmeter readings were taken at regular intervals, although it was difficult to obtain a steady reading because of a continual drift. This could have been due to changing conditions or a manufacturing fault with the voltmeter.

On the next step, we’ll consider the level of detail you need to include when it comes to describing your equipment.

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This article is from the free online course:

Technical Report Writing for Engineers

The University of Sheffield