Year 7 Science · Unit 4 · Lesson 5
Master Worksheet
Learning Goals
Observation or inference? Sort and justify
Read each statement from a student's nature walk. Decide whether it is an observation or an inference, tick one box, and write a short reason for your choice.
| Statement | Observation | Inference | Reason |
|---|---|---|---|
| The pond water is cloudy and green. | |||
| The pond is probably full of algae. | |||
| The air temperature is 14 degrees Celsius. | |||
| The frogs are hiding because it is too cold. |
Plan a fair test: senses versus instrument
Scenario
A classmate claims "I can guess the temperature of water just as well as a thermometer can measure it." This is a claim that science can actually test. Your job is to plan a fair, testable investigation that compares people's temperature guesses with thermometer readings. Remember a fair test changes only one thing at a time and keeps everything else the same.
Sample data table
The table below shows one student's results. Use it to answer the questions.
| Cup | Guess by hand (°C) | Thermometer reading (°C) | Difference (°C) |
|---|---|---|---|
| 1 | 20 | 18 | |
| 2 | 35 | 42 | |
| 3 | 30 | 25 |
(a) Fill in the difference column, then write a clear, testable question for this investigation. State the one thing you would change and the one thing you would measure.
(b) What do the results in the table suggest about how reliable a hand is at judging temperature? Refer to the differences you calculated.
(c) Evaluate this statement: "Because instruments are so accurate, scientists never need to use their senses at all." Do you agree? Justify your answer, using ideas about observations, inferences and testable predictions.
Wrap Up
In one sentence, what was the main idea of this lesson?