In science, a procedure is a detailed, step-by-step set of instructions that describes exactly how an experiment or investigation is carried out. It spells out what materials to use, what actions to take, in what order, and how to measure or record results. Think of it as a recipe for an experiment: specific enough that someone else could follow the same steps and expect similar outcomes.
The term comes up constantly in science classes and research papers, but it carries more weight than it might seem. A well-written procedure is what separates a casual observation from a real experiment, and it’s the foundation for one of science’s most important principles: that results should be repeatable.
How a Procedure Fits Into the Scientific Method
The scientific method is the broad framework scientists use to investigate questions. It typically involves observing something, forming a hypothesis, testing that hypothesis through experiments, and analyzing the results. A procedure lives inside the “testing” step. It’s the concrete plan for how you’ll actually run the experiment.
To put it simply: the scientific method is the overall strategy, and the procedure is the playbook for a single experiment within that strategy. You might have the same hypothesis but test it with completely different procedures depending on your equipment, your sample size, or what variable you’re measuring. The method asks “what are we trying to find out?” The procedure answers “here’s exactly how we’ll do it.”
What a Scientific Procedure Includes
A good procedure reads like a set of directions someone unfamiliar with your work could follow without having to guess. It typically covers:
- Materials and equipment: Every tool, chemical, organism, or instrument needed, including specific quantities, concentrations, and sources.
- Sequential steps: The actions taken in order, written clearly enough that no step is ambiguous. Instead of “heat the solution,” a proper procedure says “heat the solution to 85°C for 10 minutes.”
- Measurements and observations: How data will be collected, what units will be used, and when readings should be taken.
- Controls and variables: What’s being changed (the independent variable), what’s being measured (the dependent variable), and what’s being held constant so the results are meaningful.
The University of California Irvine’s guidelines for scientific writing put it this way: questions about “how” and “how much” should be answered for the reader, never left for them to puzzle over. If you describe an action, you also name who or what performs it. The goal is to generate results with enough detail that an independent researcher working in the same field could reproduce those results and validate your conclusions.
A Real-World Example: Titration
Titration is a common chemistry procedure used to determine the concentration of an unknown solution. Walking through it shows what scientific procedures look like in practice.
First, you inspect and clean your equipment. The buret (a graduated glass tube with a valve at the bottom) must have visible markings, a freely rotating stopcock, and no chipped glass. You rinse it with deionized water, then with your standard solution (the solution of known concentration), letting it flow through the stopcock and out the tip.
Next, you measure a precise volume of the unknown solution into a flask using a pipet, then add a few drops of a color indicator. You fill the buret with the standard solution, let a small amount run into a waste container to clear air bubbles, and record the starting volume by reading the bottom of the curved liquid surface (called the meniscus). Then you slowly add the standard solution to the flask until the indicator permanently changes color, signaling you’ve reached the endpoint. You record the final volume, subtract the initial reading, and now you know exactly how much standard solution was needed to neutralize the unknown.
Every step matters. Skipping the rinse could contaminate your solutions. Misreading the meniscus throws off your measurements. Forgetting to check for air bubbles introduces error. This is why procedures are written with such precision.
Procedure vs. Protocol vs. Method
These three terms overlap, and scientists sometimes use them interchangeably, but they have slightly different meanings.
A method is the broadest term. It describes the general approach used to investigate a question. “We used spectroscopy” or “we conducted a survey” are methods.
A procedure is the specific sequence of steps within a method. It’s the detailed instructions for carrying out the work.
A protocol is essentially a formalized, pre-approved procedure. In clinical trials and medical research, the protocol is a document describing the entire study design, including the procedures, but also participant criteria, safety measures, and data handling rules. Protocols can also cover computational workflows, operational processes, and safety checklists. The key distinction is that a protocol is typically written and approved before the work begins, while “procedure” can refer to either a planned or already-completed sequence of steps.
In a school science fair, you’ll almost always see the word “procedure.” In a published biology paper, you’ll see “methods.” In a hospital research study, you’ll see “protocol.” They’re all describing variations of the same core idea: a documented plan for how the work gets done.
Why Procedures Matter for Reproducibility
Science depends on the idea that if you follow the same steps, you should get similar results. This is called reproducibility, and it only works when procedures are described in enough detail for someone else to actually replicate them.
The National Academies of Sciences, Engineering, and Medicine has highlighted that failures in replication often trace back to incomplete reporting. If a researcher only states that she “adjusted for comorbidities” in a study population, for instance, that doesn’t tell the next researcher how those adjustments were made or give enough guidance to follow the same approach. Similarly, if a biologist doesn’t specify which reagents were used in an experiment, another lab may struggle to repeat it.
Even when a researcher reports all the critical information, seemingly minor details that weren’t documented can affect outcomes. Temperature fluctuations in a lab, the age of a chemical reagent, the brand of a piece of equipment: these things can matter. That’s why professional laboratories follow international standards like ISO 17025, which requires standardized, step-by-step work instructions and auditable documentation for every test performed. The goal is accuracy, reliability, and consistency across different labs and different people.
No second experiment can perfectly replicate a first one. Conditions always vary slightly. But a thorough procedure narrows the gap as much as possible, giving other scientists the best chance of confirming (or challenging) your findings.
Writing a Strong Procedure
If you’re writing a procedure for a school assignment, a lab report, or your own research, a few principles make the difference between something useful and something vague. Use specific measurements instead of approximate language: “add 25 mL” rather than “add some.” Write steps in chronological order, numbered sequentially. Identify every material and piece of equipment before the steps begin so the reader can gather everything in advance.
Each step should describe one action. “Pour the solution into the beaker and heat to 60°C” is better split into two steps, because the reader needs to know when to start heating and how to confirm the temperature. Include how long each step takes when timing matters. Mention safety precautions where they’re relevant to the step, not buried in a separate section the reader might skip.
The best test of a procedure is handing it to someone who wasn’t involved in designing the experiment and seeing if they can carry it out correctly without asking questions. If they can, you’ve written it well.