Year 5 Science: Models, shadows and evidence
Part of the Year 5 Science the earth, sun and moon chapter. Chapter overview · whole chapter on one page
Models, shadows and evidence
Scientists use models to help explain things that are too large, too far away, or too slow to see. A model of the Earth and the Sun can help us to explain day and night, but we must remember that the model is not the real thing.
A fair test with a stick and the Sun can show how the shadow changes through the day. The table records the shadow length at four times of day.
| Time of day | Shadow length (cm) |
|---|---|
| 8 o’clock in the morning | 60 |
| 10 o’clock | 30 |
| 12 o’clock, midday | 12 |
| 2 o’clock | 28 |
Key ideas
- A model helps us to explain things we cannot see directly, but it is not the real thing.
- Shadows are shortest at midday, when the Sun is highest.
- Shadows are longer in the morning and the afternoon.
- Shadows change length because the Sun appears to move across the sky.
| Time of day | Shadow length (cm) |
|---|---|
| 8 o’clock in the morning | 60 |
| 10 o’clock | 30 |
| 12 o’clock, midday | 12 |
| 2 o’clock | 28 |
Method. Find the longest shadow.
- Read the lengths. The longest shadow is 60 cm, at 8 o’clock in the morning.60 cm
- Name the time. So the longest shadow was at 8 o’clock in the morning.8 o’clock in the morning
- Write the answer. 8 o’clock in the morning
Check. The Sun is low in the morning. ✓
| Time of day | Shadow length (cm) |
|---|---|
| 8 o’clock in the morning | 60 |
| 10 o’clock | 30 |
| 12 o’clock, midday | 12 |
| 2 o’clock | 28 |
Method. Subtract the shorter shadow from the longer one.
- Read the two lengths. The morning shadow is 60 cm, and the midday shadow is 12 cm.60 and 12
- Subtract. The difference is 60 minus 12, which is 48.60 - 12 = 48
- Write the answer. 48
Check. Check: 12 + 48 = 60. ✓
Method. Think about the model.
- Think about the model. The lit side of the model is day, and the dark side is night.lit side
- Decide. So the model shows day and night, and the answer is yes.yes
- Write the answer. yes
Check. A model can help, but it is not the real Earth. ✓
Watch out
Watch out: a model is a simplified picture of the real thing. A torch is not really the Sun, and a ball is not really the Earth. Use the model to think, then check with evidence.
Try it (with your teacher). With your teacher, stand a stick in the ground, or a pencil in a lump of clay, in a sunny place outside. Mark the end of the shadow with a stone at the same time each hour, for three or four hours. Use a measuring tape to find the length of each shadow. Record your results in a table. Never look directly at the Sun.
Exam tip
Grown-up tip. Ask: “What happens to the shadow as the day goes on? Why?” Let your child compare the model and the real shadow.
Exercise 8E Models, shadows and evidence
| Time of day | Shadow length (cm) |
|---|---|
| 8 o’clock in the morning | 60 |
| 10 o’clock | 30 |
| 12 o’clock, midday | 12 |
| 2 o’clock | 28 |
Method. Read the row for 2 o’clock.
- Read the row. The 2 o’clock row shows 28 cm.28 cm
- Write the number. So the shadow at 2 o’clock was 28 cm.28
- Write the answer. 28
Check. The shadow at 2 o’clock is shorter than in the morning. ✓
| Time of day | Shadow length (cm) |
|---|---|
| 8 o’clock in the morning | 60 |
| 10 o’clock | 30 |
| 12 o’clock, midday | 12 |
| 2 o’clock | 28 |
Method. Find the shortest shadow.
- Find the shortest. The shortest shadow is 12 cm.12 cm
- Name the time. That shadow is at 12 o’clock, midday.midday
- Write the answer. 12 o’clock, midday
Check. At midday the Sun is highest. ✓
| Time of day | Shadow length (cm) |
|---|---|
| 8 o’clock in the morning | 60 |
| 10 o’clock | 30 |
| 12 o’clock, midday | 12 |
| 2 o’clock | 28 |
Method. Add the four lengths.
- Add the lengths. The four lengths are 60, 30, 12 and 28 cm.60 + 30 + 12 + 28
- Find the total. The total is 130 cm.130
- Write the answer. 130
Check. Check: 60 + 30 = 90, then 12 + 28 = 40, and 90 + 40 = 130. ✓
| Time of day | Shadow length (cm) |
|---|---|
| 8 o’clock in the morning | 60 |
| 10 o’clock | 30 |
| 12 o’clock, midday | 12 |
| 2 o’clock | 28 |
Method. Find the row with 30 cm.
- Find the row. The row with 30 cm is for 10 o’clock.30 cm
- Name the time. So the time is 10 o’clock.10 o’clock
- Write the answer. 10 o’clock
Check. The shadow shrinks as the Sun rises higher. ✓
| Time of day | Shadow length (cm) |
|---|---|
| 8 o’clock in the morning | 60 |
| 10 o’clock | 30 |
| 12 o’clock, midday | 12 |
| 2 o’clock | 28 |
Method. Read the table in order of time.
- Read the table. The shadow goes from 60 cm to 30 cm to 12 cm.gets smaller
- Choose the word. So the shadows are getting shorter.shorter
- Write the answer. shorter
Check. The Sun gets higher, so the shadows get shorter. ✓
Method. Read the watch-out box in section 8.5.
- Read the watch-out. A model is a simplified picture, and a torch is not really the Sun.not really the Sun
- Decide. So the answer is no.no
- Write the answer. no
Check. A model helps us think, but it is not the real thing. ✓
Method. Read the key ideas in section 8.5.
- Read the key idea. Shadows are shortest at midday, when the Sun is highest.shortest
- Name the time. So the shadow is shortest at midday.midday
- Write the answer. midday
Check. The Sun is highest at midday. ✓
Method. Think about the Sun in the afternoon.
- Think about the Sun. In the afternoon the Sun is lower again, so shadows get longer.lower
- Make the prediction. So the shadow at 4 o’clock should be longer than at midday.longer
- Write the answer. yes
Check. Check the prediction with the shadow test, with your teacher. ✓
Method. Think about the height of the Sun.
- Think about the Sun. At midday the Sun is at its highest in the sky.highest
- Write the reason. So the shadow is shorter at midday than in the morning.shorter
- Write the answer. Accept any sentence that says the Sun is higher in the sky at midday, so the shadow is shorter.
Check. A higher Sun casts a shorter shadow. ✓
Method. Think about models and evidence.
- Think about the model. A model of the Earth and a torch helps us see how day and night happen.helps us see
- Think about the check. The model is simplified, so we check it with evidence such as shadows.check it
- Write the answer. Accept any two sentences that say a model helps us to think about the Earth turning and the Sun, but the model is simplified, so we must check it against evidence.
Check. A model is useful, but evidence decides. ✓