Year 4 Changing States

In Science this term, Year 4 are learning all about ‘States of Matter’. In today’s lesson, the children undertook some investigations into how materials can change states.

Materials can be in three different states: solid, liquid or gas. When a solid turns into a liquid it is called melting. The temperature at which a solid material melts is called its melting point. Different materials have different melting points. When a liquid turns into a solid it is called freezing. The temperature at which a liquid material freezes is called its freezing point. Different materials have different freezing points.

Melting and cooling

Melting Chocolate

The first investigation was to find out what temperature chocolate will melt and how long it would take. Year 4 were given the following scenario: Maya is getting the food ready for her birthday party, and wants to make some chocolate crispy cakes. Her party is only a few hours away, so she needs to make them fast! She needs to know the best temperature for melting chocolate.

To help Maya work out how long it would take, we placed a piece of chocolate in a foil tin and floated each tin on a different temperature of water. We measured how long it took for the pieces of chocolate to melt at the different temperatures.

The children identified that the higher the temperature of the water, the quicker it melted the chocolate. In bowl 3 the temperature of the water was 30 degrees and it didn’t melt the chocolate at all.

The Three States of Water

Water can be in one of three states – solid, liquid or gas. The children investigated how water changes state, the processes that cause it to change and the temperatures at which it changes.

Ice Cube Investigation

In this activity, two ice cubes were placed on some cling film stretched over a container of warm water. The children then discussed and answered the following questions: What do you see in the container? What can you observe on the cling film? What processes are occurring?

They noticed that the ice began to melt on the top of the clingfilm and that there were signs of condensation on the clingfilm.

Salt and Ice

Two ice cubes were put in two bowls and a teaspoon of salt was poured onto one ice cube. The children observed what happened over a few minutes. They predicted that the ice would melt and the majority agreed that the temperature in both bowls would increase as the ice melted. Freya disagreed and thought the sale would decrease the temperature in the bowl and she was correct! The temperature decreased to -11.8 degrees!