1.4 Scientific Investigation in Biology
Learn the eight steps of a scientific investigation and the framework for writing an experimental biological report.
Learning Objectives
- State the eight sequential steps in carrying out a scientific investigation.
- Identify the key components of an experimental report framework.
- Describe the procedure, variables, and safety precautions involved in testing the effects of vigorous activity on pulse rate.
The 8 Steps of a Scientific Investigation & Measuring Pulse Rate
A scientific investigation follows a systematic sequence of eight steps. The pulse rate is measured by placing two fingers on the wrist.
Identifying problems
Problems that can be tested using a scientific investigation.
Forming a hypothesis
A proposed testable statement formulated to explain a problem.
Identifying and controlling variables
Manipulated, responding and fixed variables, plus data collection method.
Planning and carrying out
Plan and carry out the scientific investigation.
Collecting data
Record the data obtained from the investigation.
Interpreting data and results
Use scientific reasoning to interpret the data.
Forming a conclusion
State whether the hypothesis is accepted or rejected.
Writing a report
Write a complete experimental report.
Measuring Pulse Rate
Activity 1.1: Pulse Rate
Count the pupil's pulse for one minute before the activity. The pupil then carries out a vigorous activity for three minutes. After the activity, count the pupil's pulse again for one minute and record the results in a table.
Short Explanation
What is a scientific investigation?
A scientific investigation proves the validity of a stated hypothesis. Conducting an investigation requires following a systematic sequence of steps, starting from identifying a testable problem through to writing a final scientific report. A written report is essential to validate that the experiment has taken place.
The eight steps
1. Identifying problems
2. Forming a hypothesis
3. Identifying and controlling variables and data collection method
4. Planning and carrying out a scientific investigation
5. Collecting data
6. Interpreting data and results through scientific reasoning
7. Forming a conclusion
8. Writing a report
Why write a report?
Writing a report provides proof that an experiment was conducted. If a report is not written, the experiment will be considered invalid.
Activity 1.1: Variables
Manipulated variable: Vigorous activity
Responding variable: Pupil's pulse rate
Fixed variable: Pupil
Try to Answer First
Answer in your mind, then press “Check Answer”.
Why is an experiment considered invalid if a report is not written?
In Activity 1.1, what is the fixed variable?
What condition must be met when taking a pupil's pulse rate before the activity?
Common Mistakes
- Omitting the written report: believing the experiment ends after collecting and interpreting data, forgetting that without a report, the investigation remains invalid.
- Scrambling the sequential order: reversing steps such as interpreting data before data collection, or forming a conclusion before interpreting results.
- Inappropriate subject selection: failing to screen for health issues, allowing pupils with breathing or cardiovascular problems to engage in vigorous physical activities.
Concept Misunderstandings
A scientific investigation is only valid if the hypothesis is accepted.
The validity of an investigation depends on following proper scientific methods and writing a report; a hypothesis can be either accepted or rejected based on the actual results.
Any finger, including the thumb, can be placed anywhere on the hand to measure pulse rate.
The pulse must be counted specifically by placing two fingers on the wrist.
Summary
- Scientific investigations are systematic methods used to test hypotheses through eight specific steps.
- The eight steps are: identifying problems, forming a hypothesis, identifying and controlling variables, planning and carrying out the investigation, collecting data, interpreting data, forming a conclusion, and writing a report.
- An experimental report documents all aspects of the investigation, including problem statement, hypothesis, variables, apparatus, procedures, data tables, discussion, and conclusion.
- In Activity 1.1, the manipulated variable is vigorous activity, the responding variable is the pupil's pulse rate, and the fixed variable is the pupil.
- Pupils with breathing or cardiovascular problems must not take part in the vigorous physical activity.
Short Activity
Objective: test your understanding of scientific investigation steps and the experimental report framework.
A. Objective Quiz
What is the consequence if a student does not write an experimental report after completing an investigation?
What is the responding variable in Activity 1.1?
B. Fill in the Blanks
Scientific investigations prove the of a hypothesis that has been made.
In Activity 1.1, the pulse is counted by placing two fingers on the .
C. Matching / Drag and Drop
Match each step number of a scientific investigation to its correct action. On a phone, tap a choice first, then tap the matching box. Tap the Answer Choices area to return a selected item.
C. Match the Step Number to Its Action
Write the correct step number next to each action.
| Investigation Step | Step Number |
|---|---|
| 1. Identifying problems that can be tested using a scientific investigation | |
| 2. Forming a hypothesis | |
| 3. Forming a conclusion | |
| 4. Writing a report |
Answer choices: Step 1 • Step 2 • Step 7 • Step 8
