Hold on tight

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

Water can exist in three states: water (liquid), ice (solid) and water vapour (gas). When the temperature falls below 0 degrees centigrade, water freezes. 

Icicles form when the weather is sunny but the temperature is below freezing. The sun melts some of the snow or ice that has built up, for example, on a roof. As the water drips off the edge of the surface, the below-freezing temperature causes the drops to freeze again and create the base of an icicle. If the sun continues to melt snow or ice on the roof, then water continues to drip down the slowly-growing icicle increasing its length and width. 

This can also happen when there is a poorly-insulated building and the snow melts because of the building’s warmth.  

As hot air rises, the air at the top of the icicle is warmer. This means the icicle will be warmer at the top, so the water will drip down the icicle rather than simply freezing at the top. 

Watch out for...  

Children often thinking wrapping wool fabric around a block of ice will cause it to heat up and melt. Heat insulators like wool do not allow heat to move through them easily.  

This does not need to be corrected during the session, but you can pick it up later. 

Take it further

Activities 

Children can observe the three states of water by heating a small ice cube in a foil tray over a lit tealight. They can observe the ice melt and the water evaporate.  

Health and safety: Make sure the children’s hair is tied back and that the tealights are in sandboxes or on metal trays. You can buy tea light stands to place the foil tray on.

This CLEAPSS activity has children observing melting ice cubes on a hot water bottle. Most schools are members of CLEAPSS; check with your school office. 

This CIEC activity looks at the use of salt as a de-icer for roads.

This activity investigates insulating ice cubes. You could also investigate melting by leaving a variety of materials outside on a hot sunny day. Children could make regular, careful observations to see what happens over the course of a day. 

Linked Explorify activities- our recommendations: 

Have you ever had an ice cream melt?, White crystals,  Frozen in motion, Snowflake, What if water couldn’t freeze? and Ice-lollies.  

Watch 

How icicles are made. This BBC video explains changing states. 

Cross-curricular 

This is a recipe for making frozen bananas lollies which involves freezing and melting.