Year 7 Science · Unit 4 · Lesson 14
Apply Worksheet
Learning Goals
Observation or inference?
Read each statement from a crater investigation. Decide whether it is an observation (something you directly notice or measure) or an inference (a conclusion you work out). Write your answer in the right column.
| Statement | Observation or inference? |
|---|---|
| The crater measured 42 mm across with a ruler. | |
| The ball must have been moving faster when it landed. | |
| A higher drop probably gives more energy to the ball. | |
| Flour was pushed up into a ring around the dent. |
Investigation context
A class wants to model how craters form on the Moon and the rocky planets. They drop the same marble into the same tray of flour from five different heights: 20 cm, 40 cm, 60 cm, 80 cm and 100 cm. Each time, they smooth the flour flat and measure the crater diameter across the top with a ruler. They repeat each height three times to make their results more reliable.
(a) Sort each part of the investigation into the correct column. Write independent, dependent or controlled next to each one.
| Part of the investigation | Type of variable |
|---|---|
| The drop height (20, 40, 60, 80, 100 cm) | |
| The crater diameter measured each time | |
| The same marble used every time | |
| The same depth of flour in the tray |
(b) Why do the students repeat each drop height three times instead of just once? Explain how this makes their results more reliable.
(c) Predict the trend. As the drop height increases, what do you expect to happen to the crater diameter, and why?
1. Explain how a powerful instrument, such as the Parkes radio telescope (Murriyang) or a space telescope, helps scientists observe the Universe more accurately than the human eye alone.
2. The crater model and a real Moon crater are not exactly the same. Give one way the model is similar to a real impact, and one way it is different.
Wrap Up
In one sentence, what was the main idea of this lesson?