The Big Drip - Key Stage 2

INTRODUCTION

The Big Drip is based on Attainment Target 3 of the National Curriculum for Science and these notes are intended as a guide to the scientific content of the play should teachers wish to undertake some preparatory work with their pupils. However we do aim to present the play in such a way that the scientific content becomes self-explanatory so preparatory work is not essential.

The topics covered in the play are materials and their properties, solids, liquids and gases, mixtures and compounds, the separation of mixtures, changes of state and indicators.

MATERIALS AND THEIR PROPERTIES

Everything on Earth can be said to be made of some sort of material. Most substances on Earth are solids at normal temperatures and it is the group of solids that is used extensively by Man. All materials have individual characteristics, or properties, which govern how they are employed.

Our story begins at the Missing Material Bureau where we meet Detective T.Copper. With his help, and the help of his new assistant Miss Spendapenny, we learn how to classify materials according to their properties - eg. glass can be described as see-through, hard, cold and smooth, wood as warm, natural, brown in colour and rigid etc. T. Copper and Miss Spendapenny take it in turns to describe a material using only its properties and the audience has to work out which material it is. Through a song we discover that certain properties are linked to the uses of a material - eg. metal is strong, hard and conducts heat and electricity so is used for a kettle, whereas plastic is pliable, man-made and can be coloured and moulded so is ideal for a multitude of everyday items.

In the classroom the children can try to find as many uses as they can for various materials - wood, glass, metal, paper, cloth, plastic, sand - and then explain which are the properties which govern its uses. They can then try to identify the properties which are common to each family of materials and classify each material using the appropriate properties - what makes something a metal or wood or plastic etc.?

SOLIDS, LIQUIDS AND GASES

There are three states of matter. All substances on Earth exist as either a solid, a liquid or a gas. In general solids are hard and rigid and have a definite shape which is often difficult to change. Liquids have different properties. They are fluid and flow and have no definite shape but take on the shape of the container they are in. Gases have no definite shape or size and usually we cannot see them but they will fill whatever vessel or space they are in.

Again at the Bureau another classification is taking place. We discover the three states of matter and define them with help from the audience. The different properties are discussed and we show that all three states can be found in a can of fizzy drink - the can is a solid, the drink a liquid and the fizz a gas.

In class the children can explore the variety and uses of solids, liquids and gases. What are the most common uses for each state? Where might you find a solid, a liquid and a gas in a bicycle and a car? Can they think of any other objects where all three substances are used? By considering a viscous substance, like thick custard, the children can discuss whether the substance is a liquid or a solid and why they would define it as such using the properties of solids and liquids to substantiate their case.

MIXTURES AND COMPOUNDS

A mixture of substances can be separated physically into its constituent parts. Most foods are mixtures, eg: salad dressing is a mixture of oil and vinegar. Air is one of the most important mixtures, being mainly nitrogen and oxygen plus many other gases.

A compound however is a combination of substances, or materials, that have been chemically joined, where their individual chemical structure has been altered in the bonding of the materials. They cannot be physically separated from each other. Two commonly found compounds are concrete, made from cement, sand, stone chips and water where the chemical reaction takes place at a low temperature to form a strong solid, and soap, a compound formed from oil, sodium hydroxide and water where the mixture is heated to enable the reaction to take place to form soap.

Our story moves on and we find ourselves at Dr Boffin's laboratory where a discussion takes place on the subject of mixtures and compounds. Dr Boffin demonstrates a mixture by using his favourite recipe for pickled onion flavoured fairy cakes, and explains that before the mixture is cooked all the ingredients can be separated out again. Once cooked, however, the cake mixture chemically changes to form a compound and becomes a cake.

In class the children can try to think of other instances, such as baking, where a mixture becomes a very different substance when a chemical reaction takes place to form a compound.

SEPARATING MIXTURES

As mixtures are not chemically joined they can be separated back out into their constituent parts. There are several techniques: dissolution, filtration, evaporation, distillation and chromatography.

Dr Boffin is required to separate out a mixture of sugar and a mysterious added ingredient to discover the identity of the mystery material. To do this he uses filtration and dissolution. He demonstrates the techniques to the audience by dissolving the sugar in water and then filtering the solution to separate the added ingredient from the sugar.

In class the follow up work could include separating muddy water, retrieving the salt crystals from salt solution whilst collecting the pure water or separating the dyes in black ink.

CHANGES OF STATE

Substances on Earth can, with changes of temperature, change their state. The most obvious example is red hot lava, being liquid rock, where the temperatures have increased to such an extent that the rock has melted. Nitrogen gas requires very low temperatures, well below the freezing point of water, to liquefy.

Using water as an example we discover that a substance can exist in more than one state of matter. Six volunteers from the audience are required to represent water particles. Firstly they pack tightly together to become a solid, ice, where the bonds between the particles are strong and hold them in a fixed shape. We establish that by heating the ice it will melt and become a liquid. The children then move apart but remain bonded by holding hands to form a liquid. They see that although they are still bonded together they have much more freedom of movement and it is this freedom that allows a liquid to change its shape. When enough heat energy is introduced the water will boil and become a gas so the children are asked to drop their hands, showing that in a gas the bonds between the particles are broken, and they are free to move about wherever they like.

In the classroom the children could discuss the changes of state described by the words melting, evaporating or vaporising or boiling, condensing, solidifying or freezing and try to write a state by state chart of the changes in state of the special water stolen by the Tuttifrutti Brothers using the right terms from the list above. They could think of different substances that exist in two or more states on Earth and write down where you might find them.

INDICATORS

S P L Sorensen (1868-1939) introduced the pH scale to measure the concentration of hydrogen ions in a solution - the more ions the stronger the solution. It was discovered that the amount of ions in a solution affected the colour of certain natural dyes and using this knowledge the dyes were used as indicators to test for acidity and alkalinity. Red cabbage dye produces an indicator as does lichen which is used for Litmus paper but these indicators will tell you only that something is an acid or an alkali, not by how much. Universal paper was created to give a scale of indication, so that it can be seen how acidic or how alkaline a solution is. It is formed by combining several different indicators to create what is known as the pH scale.

In the play, using Universal indicator, we chart the strengths of acids and alkalis and use it to prove that two different mixtures have the same acidity.

In the class room you can create your own indicator by boiling up red cabbage and collecting the juice. If you then pour in an acidic solution the indicator will turn green. Then slowly add an alkaline solution and find our how much was needed to neutralise the acid and turn the indicator back to its original colour.

AT THE END OF THE PLAY

These are the topics covered in the performance. If the children or staff have any questions about the play there is a question and answer session at the end of the presentation where the performers will be happy to answer any queries they can. We trust these notes are a useful guide and that the presentation will afford plenty of follow-up work in the classroom.

Show Requirements

The actors will be arriving approximately forty minutes prior to the start time in order to set up and will need to have access to the school hall from then. They bring the set, lighting and sound equipment with them so only need access to a plug socket. They’ll need a space approximately 15’ wide by 10’ deep with the children sitting in front, either seated or on the floor. The show works well ‘on the flat’ but if it’s more convenient for the actors to use your stage, please let them know on arrival. Quirks in the Works lasts one hour.