Looking at states Year 4, Topic 3, Switched on Science

Key Vocabulary State of matter Solid Liquid Gas Matter Temperature Melting Freezing Melting point Freezing point Boiling point Evaporation Condensing Water cycle Boiling

In this topic you will: group materials together using their properties recognise solids, liquids and gases observe how materials change from a solid to a liquid or a liquid to a gas measure temperature accurately explore patterns in freezing and melting find out what the ‘water cycle’ is.

Unit 1: What a racket! Can you: group materials based on their properties? recognise that materials exist in the solid, liquid and gas forms? describe what happens when ice melts?

Let’s think like scientists Does air just contain one material? Are all liquids the same? Is glass a solid or a liquid? What is meant by “Change of State”? Can wood only exist as a solid? Can you freeze air into a solid?

Right or wrong? Are these ideas right or wrong? Materials only exist in one state. Ice is a different material than water or steam.

Answers No. Nearly all materials exist as a solid, liquids and a gas. No. They are all the same material.

Did you know? Water is a special substance. The Celsius scale is based on the temperature at which it changes to ice (0 degrees) and steam (100 degrees). There are also other temperature scales. The most common of these is the Fahrenheit scale.

The three states of matter Materials can exist in three states : solids, liquids and gases. The state a material is in depends on the temperature. Water is in its solid state (ICE) at 0 o C. It exists as liquid water between 0 o C and 100 o C. Above 100 o C it exists in the gas state (STEAM).

Solids SOLIDS: They are hard. They are difficult to compress. They keep their shape. You can hold it in your hands.

Is a sponge a liquid? No it is a solid. You can squash a sponge but it is the air you are squeezing not the solid sponge!

Liquids LIQUIDS: They pour and are runny. They take the shape of their container. You cannot hold liquids in your hands (it all drains away!)

Is sand a liquid? You can pour sand, so is it a liquid? The correct answer is no. You need to think of each grain of sand as a tiny solid. By this reasoning, rice is also a solid!

What state is it in? What state are these materials usually found in? Sponge Sand Thick cream Butter Explain your reasoning.

Gases Gases: They usually cannot be seen. They fill their containers. They escape from unsealed containers. They spread out to fill all the space available. You cannot hold gas in your hands (it floats away!)

Hunting the materials Go on a material hunt around your school. Search out the solids, liquids and gases. Put your results in a table like this one.

Make a chart Make a wall chart grouping materials into solids, liquids and gases. Use this to define what a solid, liquid and gas is.

Investigate melting ice Place some ice cubes in a beaker. Add a thermometer and record the temperature every minute until the ice fully melts. Put your results in a table. Describe what you have found out.

Unit 2: Ziggy’s party Can you: describe what happens when a solid melts? describe what happens when a liquid freezes? say what ‘boiling’ and ‘evaporation’ are? measure temperature accurately?

Let’s think like scientists Why do we add salt to frozen paths in winter? What does the salt do to the ice? Where can you see changes of state happening and occurring?

Right or wrong? Are the following ideas right or wrong? Only the liquid water boils. There are no temperatures below zero or above 100 degrees Celsius. Every material freezes at zero degrees Celsius.

Answers No. Every liquid has its own unique boiling point. No. You can get to 212 degrees below zero degrees Celsius, and technically there is no limit to how high you can go! No. Different materials freeze at different temperatures.

Not all solids are hard!

What temperature does chocolate melt at? Will chocolate melt in a fridge? The temperature inside a fridge Is usually above 0 o C. Will chocolate melt in your mouth? What do you think the melting point of chocolate is?

Melting points When a solid material melts it turns into a liquid, because heat has been given to it. You can tell if a material is melting because you can see both its solid and liquid states. Pure water and gold melt very suddenly because they are pure. Margarine and chocolate melt over several degrees because they are mixtures of substances.

Why do we add salt to icy roads in winter? A mixture of salt and water freezes at a lower temperature than pure water. Adding salt to icy roads melts the ice. Adding salt to ice can be used to cool the surroundings.

How to make ice cream What would happen if you didn’t put it in the fridge?

Unit 3: Going round in circles Can you: describe the process of evaporation? explain how condensation and evaporation take place? link all the processes that you can find in the water cycle?

Let’s think like scientists Do all materials boil? What material has the highest boiling point? What material has the lowest boiling point? How do you predict the weather? How do tumble driers work? What does the condenser in a tumble drier do?

Right or wrong? Are the following ideas right or wrong? Only water can be found in different states. Water disappears when it evaporates. The freezing and melting points of a substance are the same.

Answers No. Many substances exist in different states. No. It changes into a gas. Yes. They are the same!

Did you know? Air freezes at minus 215 degrees Celsius!

What happens when you heat or cool water? Warming solid ice makes it melt into liquid water. Adding more heat makes it evaporate into water vapour. At 100 o C you see this as steam. When water vapour is cooled, it condenses into liquid water. If it is cooled to 0 o C it freezes and forms solid ice.

The water cycle Water continually moves around the Earth in the water cycle. The Sun evaporates water into water vapour. When the water vapour cools down it turns into liquid water and it rains. In very cold places the water freezes into snow or ice. Snow and ice when warmed up change into liquid water.

Make a cloud in a glass What you need: Beakers / thermometers / Ice / Cold baking trays / Warm water / Kettle / Foil trays / access to a freezer What to do : Put the ice in the foil container. Wait for the foil to get very cold. Pour about 1 cm height of warm water into the glass. Place the foil container and ice on top of the glass. Look carefully inside the glass.

The best way to dry clothes Ziggy has a wet shirt. He wants to wear it for a party. But he has no spin drier. Help him out. Investigate the best way to dry it. You can use salad spinners / washing lines / pegs / hair driers / fans /large sheets of paper / lamps or something else you choose. Tell your class how you did this and if the way you chose was any good.