Lesson at a Glance | He Tirohanga Whakamua
Ngā Whāinga Ako | Learning Intentions
Students will know
- The crucial difference between reliability (repeatability & small trial variation) and validity (fair testing & controlling variables).
- How to identify random measurement errors (e.g. gas bubble volume variation, timer reaction time) versus systematic errors.
- How to propose realistic, specific improvements to the method for future investigations.
Students will demonstrate
- By critically evaluating their experimental setup across 3 dimensions: reliability, validity, and improvements.
- By completing Section 9 of their Level 1 Science Biological Investigation Logbook.
Curriculum alignment
- NZC (2007) · Science · Level 6 · Nature of Science: “Begin to evaluate the suitability of the investigative methods chosen.”
Do Now | Tīmatanga Whakaaro (10 min)
Target Analogy Prompt:
"If your 3 trial readings for 10cm distance were 14, 14, 14 bubbles, but your water was secretly heating up from 18°C to 34°C, is your experiment reliable or valid?"
Unpack: It is highly reliable (all 3 trials gave identical results: tight grouping), but completely invalid because water temperature was changing during the test, meaning light was NOT the only variable affecting the bubble rate.
Evaluating Method Quality for Excellence (15 min)
"Our 3 trial repeat readings showed minimal spread (e.g. 14, 15, 13 bubbles at 10cm), giving a narrow range of ±1 bubble and confirming our method was reliable."
"Validity was maintained by using an LED lamp (low heat emission) and a glass water bath. A key improvement would be measuring gas volume in a micro-burette instead of counting bubbles."
📁 Biological Investigation Logbook — Section 9: Method Evaluation & Improvements
Students open their Level 1 Science Logbook and complete Section 9:
Section 9 Requirements:
1. Reliability Audit: Discuss the consistency of your 3 trial repeat readings. Cite trial ranges to prove data reliability.
2. Validity Audit: Evaluate how effectively your controlled variables prevented confounding factors from skewing results.
3. 2 Methodological Improvements: Describe 2 specific equipment or procedural modifications to reduce measurement error in future investigations.
Exit Verification | Ka Mutu Hoki (5 min)
Exit Check:
"My Section 9 evaluation distinguishes reliability from validity and details 2 specific methodological improvements."
Teacher Planning & NCEA Alignment
NCEA Level 1 Science Alignment (4 Credits):
- Excellence Criteria: Evaluate the investigation method by explaining how the method ensured reliability and validity, and suggesting modifications.
- Critical Inquiry: Demonstrate awareness of sources of measurement error and limitations in laboratory setups.
Vocabulary: Reliability, validity, measurement error, systematic error, random error, parallax, trial spread, methodological improvements.
Other teaching approach: Guided Viewing & Practical Investigation →