What are some properties of air? (2)
2. Show the Particle Magnifier
Note: The full version of the Particle Magnifier (Water-Air) allows users to view air and water vapor in addition to the ice / water inside the container. There is no magnifier in the air at -273°C. Nitrogen, oxygen, and all of the elements that compose our atmosphere would be solids before the temperature reached absolute zero.
Unlike the ice-water transformation, there is no emphasis on gradual change in air with temperature change. The key point to highlight is the contrast between air and water.
Remind students that this is an animation that shows what scientists think happens. At each temperature, ask students:
| Temp | Notes | Likely student observations |
|---|---|---|
| +2°C | Show water. This is a reminder to help highlight the difference between water and air. |
|
| +2°C | Show air. |
|
This is the first time students have seen air represented as distinct particles. Remind them of these key points:
- Students have evidence that air has weight, and takes up space, and is therefore matter.
- Scientists have learned that all matter is made of tiny particles too small to see.
- When tiny particles are clumped together, as they are in water, we can see the matter. (Dot Sheet 1)
- When those particles are spread apart, as they are in air, or in salt that has been dissolved in water, we cannot see the matter. (Dot Sheet 2)
Move back and forth between water and air, at different temperatures, highlighting the difference in the distance between particles.
What are your ideas now about why air is compressible and water isn't?
- There is more space between the air particles so there's room for them to move together when air is compressed (squeezed).
