Changing shadows
This Topic is About...
- I will investigate how shadows can change.
- I will explore how shadows are formed when light is blocked by an object.
- I will make a prediction and see if it is right.
- I will record results in a table and then interpret these results.
- I will describe simple patterns in results and make a conclusion from the results.
You’re going to be a science explorer!
Key Words
- conclusion
- non-standard units
- standard units
Tap to Learn the Meanings!
- conclusion: The final decision or answer you get after looking at your results.
- non-standard units: Measurement units that are not commonly used, like using hands or blocks to measure length.
- standard units: Measurement units that everyone agrees on, like metres, litres, or grams.
Great work! You’re learning important measuring words.
Looking at shadows
Do you ever see shadows in your classroom?
If there is a bright light source you may be able to see shadows made by objects. Do you ever see the shadows move or change size or shape?
A shadow can look like the object making the shadow.
Sometimes the shadow of an object looks very different to the object.
FUN QUESTION
1. Identify these things from the shadows:
- a car
- a plane
- a cyclist
- a fish
Show answer
2 — Bird (not fish)
3 — Car
4 — Plane
Think like a scientist
How can shadows grow?
You are going to investigate how the shadow of an object changes as you move the object closer to the source of light.
Use the card to make a star.
Stick the star onto the end of a wooden stick.
Hold a flashlight 30 cm from a table top, pointing down onto the paper.
Now hold the star in the light at a height of 2 cm from the table top. Draw around the shadow on the paper. Measure the width of the shadow.
Continued
Predict what will happen to the width of the shadow as you move the star towards the light source.
Describe the pattern in your results.
Make a conclusion from your results.
| Height of object (star) above table | Predicted width of shadow | Width of shadow |
| 2 cm | 2 cm | 2 cm |
| 4 cm | 4 cm | |
| 6 cm | 6 cm |
Finish this sentence:
As an object moves towards a light source its shadow gets ________.
How am I doing?
- Draw a picture of a flashlight shining on a wall.
- Draw your hand in the light and the shadow it casts on the wall.
- Explain to a friend how you can make the shadow smaller and bigger when you keep the flashlight still.
Show example ideas
- The shadow gets bigger as the star moves closer to the flashlight.
- A pattern you might see: at 2 cm the shadow is about 2 cm wide, at 4 cm it is about 4 cm, and at 6 cm it is about 6 cm.
- Conclusion: When an object is moved closer to a light source, its shadow becomes larger.