Scientific Investigation Practice

Definition and Purpose of Scientific Investigation

A scientific investigation, as defined within the curriculum at The Winchester School, is a systematically planned practical activity. Its primary purpose is to provide a structured method for answering a specific question or testing an idea, which is known as a hypothesis. To ensure validity and reliability, any investigation must be conducted fairly and safely. This involves the careful management of variables and the implementation of specific safety protocols to protect the investigator and the equipment.

Understanding and Categorizing Variables

A variable is defined as any factor or element that can change within an investigation. There are three primary types of variables that must be identified during the planning phase: independent, dependent, and controlled variables. The independent variable is the specific factor that the investigator deliberately changes. It is meant to answer the question: What am I changing? For example, in an investigation asking how the length of a shadow changes with the time of day, the independent variable is the "Time of day."

The dependent variable is the factor that is measured or observed as a result of the changes made to the independent variable. It answers the question: What happens as a result? In the aforementioned shadow example, the dependent variable is the "Length of the shadow." Finally, controlled variables are the factors that must be kept exactly the same throughout the experiment to ensure a fair test. Examples of controlled variables include using the same measuring equipment, maintaining the same location for all observations, and using the same object to cast the shadow.

The Planning Process: Aim, Prediction, and Variable Identification

The first step in planning an investigation is to define the Aim, which identifies exactly what the investigator is trying to find out. An example aim would be: "To investigate how water temperature affects the time taken for sugar to dissolve." Once the aim is established, Step $2$ involves creating a Prediction or Hypothesis. This is a formal sentence that states what the investigator thinks will happen and explains the scientific reasoning behind that belief. Predictions often follow templates such as "I predict that…" or "If… then… because…". For instance: "If the temperature of the water increases, then more sugar will dissolve in the water because the particles in hot water move faster and can break apart the sugar more easily."

Step $3$ is the formal identification of variables within the context of the experiment. Using the sugar dissolution example, the Independent variable is the "Water temperature," and the Dependent variable is the "Time taken for sugar to dissolve." Other variables must be controlled to maintain the integrity of the experiment. These include the "Amount of sugar," the "Volume of water," and the "Stirring method" used during the process.

Materials, Method, and Observation Planning

Step $4$ requires the investigator to list all materials required for the experiment. In the sugar dissolution investigation, the necessary materials include a Beaker, a Thermometer, Sugar, a Stopwatch, and a Stirring spoon. Step $5$ involves drafting a clear, numbered Method so that another person could repeat the experiment exactly. The specific steps are: $1$. Pour $100\,cm^3$ of water into a beaker; $2$. Measure the temperature of the water; $3$. Add $1$ spoon of sugar; $4$. Start the stopwatch and stir gently; and $5$. Record the time taken to dissolve.

Step $6$ focuses on Observation and Results, where the investigator decides how the gathered data will be recorded. Common methods for recording these specific results include creating a table of temperature vs. time or constructing a line graph to visualize the trends. This systematic recording allows for easier analysis of the relationship between the independent and dependent variables.

Safety Considerations and Risk Management

Also categorized under Step $6$ is the consideration of Safety. This involves thinking about potential risks and identifying ways to reduce them. General safety examples provided by The Winchester School include handling hot water carefully to prevent burns and ensuring that no water is spilled on electrical equipment, which could cause a short circuit or an electrical hazard. By identifying these risks beforehand, the investigator can maintain a safe environment for the duration of the practical activity.

Drawing a Scientific Conclusion

The final phase of an investigation is Step $7$, the Conclusion. A conclusion is defined as the answer to the question: "What did the experiment show?". A high-quality conclusion must include three distinct parts: a summary of what happened in the experiment, a statement on whether the initial prediction was correct, and a scientific reason for the outcome using key terms.

In the sugar experiment, an example conclusion would be: "The experiment shows that more sugar dissolves in water at higher temperatures. This supports the prediction because hot water particles move faster, allowing them to break apart and dissolve sugar more effectively than cold water particles. Therefore, increasing the temperature of water increases the amount of sugar that can dissolve in it." This explanation links the macroscopic observation of the dissolving sugar to the microscopic behavior of moving particles, providing a complete scientific justification for the results.