Year 7 Science · Unit 4 · Lesson 5
Apply Worksheet
Learning Goals
True or false? Fix the false ones
Circle T or F. If a statement is false, correct it on the line.
1. You can tell whether a person’s temperature is 37 °C or 39 °C by feeling their forehead.
Correct it:
2. The same bowl of water can feel warm to one hand and cold to the other.
Correct it:
3. An inference is something you watched happen with your own eyes.
Correct it:
4. An inference uses what you already know to explain an observation.
Correct it:
5. “The water was 42 °C” is more useful in science than “the water felt warm”, because other people can check it.
Correct it:
Testable or not? Sort it
A prediction is testable if a measurement or an experiment could check it. Write each prediction in the correct box. The boxes do not hold the same number of items.
Testable
Not testable
One observation, two inferences
For each observation, write a sensible inference, then a different inference that could also fit.
| Observation | A sensible inference | Another inference that also fits |
|---|---|---|
| 1. There are tyre tracks across the school oval. | ||
| 2. Every light in the house next door is off at 7 pm. | ||
| 3. The dog’s water bowl is empty. |
Read the data: the class worm farm
Scenario
A Year 7 class keeps a worm farm outside. The care sheet says these compost worms do best when the soil is between 15 °C and 25 °C. On a hot day, one student felt the soil every two hours and said how it felt. Another student pushed a soil thermometer into the same spot. At 3 pm, the first student had just come in from the hot playground.
| Time | How the soil felt to a hand | Soil thermometer (°C) |
|---|---|---|
| 9 am | Cool | 19 |
| 11 am | Cool | 24 |
| 1 pm | Warm | 29 |
| 3 pm | Cool | 31 |
Source: sample class results.
1. At which times was the soil outside the worms’ best range? Use the thermometer readings.
2. At 3 pm the hand said “cool” but the thermometer read 31 °C. Explain why the two observations disagree, and which one the class should trust.
3. Write one inference about the worms from Table 1. Then write a testable prediction, as “If … then …”, that the class could check tomorrow after moving the worm farm into the shade.
4. Jamie dips his toes in the school pool and says, “It’s too cold for the swimming carnival.” Explain to Jamie how a scientist would turn his feeling into evidence. Use the words observation, inference, instrument and prediction.
True or false
1. False: touch cannot tell 37 °C from 39 °C; you need a thermometer. 2. True. 3. False: an inference is worked out from observations; you did not see it happen. 4. True. 5. True. 5 correct = 3; 3 or 4 = 2; 1 or 2 = 1. [3 marks]
Testable or not? Sort it
Testable: the ice block; the kettle; the bean seeds; the bike tyre. Not testable: blue school bag; the cat and Perth; the full Moon. All 7 = 3; 5 or 6 = 2; 3 or 4 = 1. [3 marks]
One observation, two inferences
1 mark per row, two different inferences that fit. E.g. 1. a car drove across / a mower cut the grass. 2. the neighbours are away / the power is off. 3. the dog drank it / it was knocked over. [3 marks]
Read the data: the class worm farm
1. 1 pm, 29 °C (1) and 3 pm, 31 °C (1): both above 25 °C. [2 marks]
2. The student’s hand had just been in the hot playground, so the warm soil felt cool compared with the hand: touch was fooled (1). The thermometer gives an exact number (1) that anyone can check and repeat, so the class should trust 31 °C (1). [3 marks]
3. Inference, e.g. the soil gets too warm for the worms in the afternoon (1). Prediction, e.g. if the farm is in the shade, then at 1 pm tomorrow the soil thermometer will read 25 °C or less (1). [2 marks]
Question 4
Marking guide: 1 touch is rough and can be fooled (toes that were warm make water feel colder) and gives no number; 1 use a thermometer; 1 it gives an exact number in °C that others can check and repeat; 1 the reading is the observation; 1 “too cold for the carnival” is an inference worked out by comparing it with a known safe temperature, and could be wrong; 1 a testable prediction, e.g. if the pool cover stays on for two sunny days, then the thermometer will read at least 2 °C higher. [6 marks]
Model answer: Jamie’s toes give a rough feeling that can be fooled, and no number. A thermometer reading, say 19 °C, is an observation anyone can check and repeat. Comparing it with a comfortable swimming temperature lets us infer whether the pool is too cold, though an inference can be wrong. Prediction to test: if the pool cover stays on for two sunny days, the thermometer will read at least 2 °C higher.
Common error: giving only one inference as “the answer”. An inference can be wrong, so more than one can fit.