White crystals

Activity overview

Run the activity

You will be zooming in and out of the image above – starting very close and stepping back slowly.

1. Start by asking everyone:

• What do they think the image is and why?
• What does the image remind them of and why?

2. Every time you zoom out, ask the class:

• Can they describe the colours, shapes and textures?
• What do they think the image is now – have they changed their minds?

Background science

The ice that forms on car windscreens can do so in different ways, depending on air temperature and the amount of moisture in the air. Sometimes ice is formed on wet windscreens when the temperature drops overnight, and the water turns to ice. 

At other times, however, ice can form on dry windscreens as the moisture in the air touches the freezing windscreen and turns from a gas (water vapour) to a solid (ice) without going through an interim liquid stage. This is why the ice on car windscreens does not always look the same and is sometimes harder to scrape off than on other days.

De-icer works by mixing with the frozen water thus making a solution that freezes at a lower temperature than pure water. This means that it is liquid at temperatures where pure water would freeze.

Take it further

Children will have further opportunities to think about changes in water with the Explorify Problem Solver activity Build an ice sky scraper.