Unit 4 Area of Study 3 requires students to undertake a student-designed scientific investigation related to biodiversity, environmental management, climate change and/or energy use. Strong investigation design is essential for generating valid and reliable results.
Scientific investigations in VCE Environmental Science aim to:
- Generate original primary data to answer a specific research question
- Apply systematic, reproducible methods
- Develop skills in experimental design, data collection, analysis and communication
- Build understanding of the nature and limitations of scientific evidence
A well-designed investigation addresses six key elements:
| Element | Questions to Answer |
|---|---|
| Aim | What overarching goal does this investigation serve? |
| Research question | What specific, testable question is being asked? |
| Hypothesis | What is the predicted outcome, and why? |
| Methodology | What general approach will be used? |
| Method | What specific procedures will be followed? |
| Variables | What will change, what will be measured, what will be kept constant? |
VCE Environmental Science recognises multiple methodologies:
| Methodology | Description | Example |
|---|---|---|
| Controlled experiment | Deliberately manipulate one variable; all others controlled | Effect of temperature on decomposition rate |
| Fieldwork | Collect data in natural settings | Species diversity survey in two habitat types |
| Case study | In-depth investigation of a specific real-world situation | Analysis of management outcomes for a particular wetland |
| Correlational study | Identify relationships between naturally varying variables | Correlation between rainfall and bird species richness |
| Modelling | Use mathematical or physical models | Climate model simulation of temperature under different emissions |
| Literature review | Analyse and synthesise existing published research | Review of impacts of wildfire on soil carbon |
| Classification and identification | Systematically categorise organisms or environmental features | Vegetation mapping using quadrats |
Understanding variable types is fundamental to experimental design:
| Variable Type | Definition | Example |
|---|---|---|
| Independent variable | The variable deliberately changed by the researcher | Temperature of water (set at 10°C, 20°C, 30°C) |
| Dependent variable | The variable measured to assess the effect | Number of macroinvertebrate species |
| Controlled variables | Variables kept constant to prevent confounding | Same volume of water, same container size, same observation time |
| Extraneous variables | Factors that may influence results but are not the focus | Weather; observer skill; time of day |
A good research question specifies the relationship between independent and dependent variables and is testable and measurable.
A scientific hypothesis:
- Is a testable, falsifiable prediction
- States the expected relationship between independent and dependent variables
- Is supported by prior knowledge or theory
Format: “If [independent variable] is [changed in specified way], then [dependent variable] will [predicted change], because [mechanistic reasoning].”
Example: “If the proportion of native vegetation cover is higher, then Simpson’s Index of Diversity of bird species will be higher, because native vegetation provides greater structural diversity and food resources.”
Students must identify the environmental science concepts relevant to their investigation and define key terms. For example:
- An investigation on species diversity requires understanding of sampling methods, SID, and the concept of biodiversity
- An investigation on carbon storage requires understanding of the carbon cycle and sequestration processes
STUDY HINT: Before designing an investigation, write out the aim, research question, hypothesis and variable list explicitly. Many methodological problems trace back to a poorly defined question or hypothesis. VCAA assessors look for internal consistency — the method must logically follow from the research question.
