Investigating Living Systems
Scientists do not just describe living systems. They investigate them. This lesson shows how to ask a living-systems question, plan a safe method, collect or use data, identify patterns and write an evidence-based conclusion.
Download this lesson's worksheet
Use the PDF for classwork, homework or revision. It includes key ideas, activities, questions, an extend task and success-criteria proof.
Q1: If you wanted to investigate a question about a living system, what would you need besides just a guess?
Write a first answer before reading. Think about evidence, data and method.
Q2: Have you ever measured your pulse after running? What did you notice, and how is that like a scientific investigation?
This prepares you for the real-world anchor later in the lesson.
Know
- living-systems investigations need a question, method, data and conclusion
- safe and fair procedures matter
- conclusions should come from evidence
Understand
- investigation is more than just observing once
- patterns in data help explain system behaviour
- secondary-source data can also support investigation
Do
- identify the parts of a simple investigation
- process and interpret data from a living-systems question
- write evidence-based explanations and conclusions
A Living-Systems Investigation Follows a Clear Evidence Path
Good scientific investigation is structured. It does not jump straight from a question to a claim.
At Stage 4, students should be able to recognise the core sequence of a simple investigation: ask a question, make a prediction, plan a safe method, collect data, find patterns and then write a conclusion supported by the evidence.
Question and prediction
- start with a testable living-systems question
- make a reasoned prediction
Method
- use safe, fair and clear steps
- collect useful information
Data and pattern
- record observations or measurements
- look for trends, changes or relationships
Conclusion
- use evidence from the data
- explain what the data suggests about the living system
A Simple Living-Systems Investigation Can Use Primary or Secondary Data
One Stage 4 example is investigating how exercise affects breathing rate or pulse rate using safe classroom procedures. Another example is using secondary-source data about plant water uptake or transpiration. In both cases, the key is the same: process data and use it to explain system behaviour.
| Condition | Breathing rate (breaths/min) | Pattern |
|---|---|---|
| Resting | 14 | Lowest recorded rate |
| After short exercise | 24 | Rate increased |
| After recovery | 17 | Rate dropped toward resting value |
Conclusions Must Be Based on Data, Not Just Opinion
A conclusion should answer the investigation question using the evidence collected. At this level, that means referring to patterns in the table, graph or observations, and linking them back to the living-system idea being studied.
This is why Working Scientifically matters in this unit. Learning about living systems is stronger when students can ask questions, process information, identify patterns and justify conclusions with evidence.
Misconceptions to Fix
Wrong: A conclusion should always agree with the prediction no matter what the data shows.
Right: A scientific conclusion must come from the data, even if the result is different from what was predicted.
Wrong: Only laboratory experiments count as scientific investigations.
Right: Investigations can use primary data you collect yourself or secondary data from published sources.
Right: Unexpected data is still valuable. It can lead to new questions and deeper understanding of the living system.
Diagram 2: Data Table Example
Annotated table showing breathing rate data with highlighted patterns and trends.
1. Investigation structure
A scientific investigation uses a question, prediction, method, data and conclusion.
2. Data use
Data should be processed to identify patterns, trends or relationships.
3. Evidence-based conclusion
A conclusion should come from the data, not just from an expectation.
4. Living-systems focus
Investigations help explain how living systems behave and respond under different conditions.
Activities
Activity 1: Plan the investigation
Write a simple living-systems question and a prediction for an investigation about breathing rate, pulse rate or plant water movement.
Activity 2: Use the data
Using the example table in the lesson, write one pattern and one evidence-based conclusion.
Claim-Evidence-Reasoning Frame
Claim: State what the data shows about the living system.
Evidence: Quote specific numbers or trends from the table.
Reasoning: Explain why those numbers support your claim about how the system responds.