Section 2: Exploring · PDF file · 2016-09-23l supported pupils as they carry out their own science investigations ... And if we don’t know – or can’t find out yet ... Make

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Section 2: Exploring solids

ContentsSection 2: Exploring solids 3

1. Inquiry-based learning 32. Group work to investigate solids 43. Investigating irreversible changes 5Resource 1: Making a zigzag book 7Resource 2: Looking at properties of solids 7Resource 3: Lesson plan on solubility 9Resource 4: Disappearing ice cube race 11Resource 5: Molecules and atoms 12

2 of 13 Friday 23 September 2016

Section 2: Exploring solidsKey Focus Question: How can you encourage pupil inquiry to explore properties andchanges in solids?Keywords: solids; inquiry; properties; investigation; rust; discussion

Learning outcomesBy the end of this section, you will have:

l supported pupils as they carry out their own science investigations (inquiry-basedlearning);

l explored different ways to present the results of their investigations;l used informal discussion with your pupils to share ideas and develop interesting

areas of inquiry.

IntroductionThe emphasis in this section is on one state of matter – solids. We consider how toencourage pupils to inquire into the origin of the solids they encounter daily. You will helpthem learn about these solids and communicate what they learn to each other.To do this we use an approach sometimes known as inquiry-based learning – learning byfinding something out for yourself. This is very different from being told something,because the pupils have to wrestle with their own ideas and explain their thinking.

1. Inquiry-based learningFor solids we can ask: ‘Where does this come from?’ Or: ‘What are its properties?’ And:‘Can it be changed?’ (This often involves much more active learning than simply listeningand hoping to remember. And if we don’t know – or can’t find out yet – there is always thepossibility that one day, we will be thrilled to come across the missing information.)Some solid substances are found naturally; others are manufactured. For example sandis a natural material and glass is a manufactured material. In fact, glass is manufacturedfrom sand. Do you know what the actual process involves? Try to find out, and you aredoing inquiry-based science.Similarly, wood is a natural material obtained from trees, and paper is made from wood.Certain wasps chew wood into pulp to process it into ‘paper’ that they use to build the cellsof their nest. People have discovered how to do the same thing. You could extend yourinquiry and experiment with making your own paper from pulped wood.Good starting points for this approach are informal discussions where pupils share ideas,raise questions and develop threads of inquiry that interest them. Case Study 1 showshow one teacher encouraged inquiry in her pupils. In Activity 1, you take this further witha class display and accompanying books made by your pupils.



Case Study 1: A game – ‘I wonder where this came from…?’Whenever Jessica in Kampala, Uganda, had a little spare time in the school day, sheplayed ‘the wondering game’ with her class (or the children left behind while others went tochoir practice). One pupil would have a turn to pick up something – anything – and ask, ‘Iwonder where this came from?’ Then everyone would put their heads together and sharewhat they knew and thought, agreeing and disagreeing and building ideas as they talked. Itwas very informal. But it always amazed Jessica that pupils would come back some dayslater with more information from home or having noticed something in a book or magazine.

The wondering game seemed to act like a key, opening the door to pupils’ curiosity. Shewondered if there was a way to make this part of formal science lessons.

Activity 1: Zigzag information booksInteresting materials gathered by pupils can be displayed in a classroom ‘science museum’.Agreed facts for each material are written on cards to support the display, just like in a realmuseum. The display grows throughout the term.

When you have enough different materials, ask pairs of pupils to make little informationbooks to add to the display (see Resource 1: Making a zigzag book).

Make sure that you give your pupils time and help to write drafts and plan the layout of thebooks they make, so that they can be really proud of their work. This also gives you achance to ensure that the scientific information is accurate. Try to encourage titles like: Thestory of glass; How cement is made; From trees to books; Where does salt come from?How to make your own glue.

Older pupils could make the books for younger pupils to read.

What differences did you notice between the first drafts and the finished books? Did youask pupils to comment on each other’s books?

2. Group work to investigate solidsIn Section 1 we considered properties of matter when we compared the compressibility ofsolids, liquids and gases. Now we consider a few more properties in relation to solids.Here is one to think about. Why is it that some solid objects feel cold to the touch andothers don’t? Think of a wooden spoon and a metal spoon. When we first pick them up offthe table, they must be at the same room temperature – yet the metal spoon feels colder.Some materials carry, or conduct, heat better than others. Metals have the property ofbeing good thermal conductors. The metal spoon conducts heat away from our hand andhence feels colder. The wooden spoon is a poor thermal conductor – it is a good thermalinsulator.In Activity 2 you investigate the property of solubility with your pupils. What otherproperties could you investigate? Electrical conductivity? Density?Case Study 2 shows how a teacher with a large class supported groups of pupils toinvestigate one particular group of materials. (See Key Resource: Working with largeand/or multigrade classes.)



Case Study 2: Properties of metalsOn a Monday, Xoliswa Mthethobrings from home a range of different metal items anddisplays them on her table at the front of the class. They include a gold ring, old silver andcopper coins, iron, steel and brass nails and screws, and wires of different sorts.

While the rest of the class is busy with other work, she gathers the group that will inquireinto and investigate the properties of metals around her. They handle and discuss what isdisplayed. They argue about whether metals bounce. They start to raise questions: Are allmetals shiny? Which is the hardest/strongest metal? Is tarnishing and rusting a property?

Xoliswaalso suggests some questions: Do all metals conduct electricity? What aboutmagnetism? What are alloys? They realise that there are many properties to beinvestigated, but some at a later stage. (See Resource 2: Looking at properties ofsolids for more ideas about how to organise a lesson on solids.)

She supports them for the week as they prepare to present the results of their inquiry. Nextweek, another group will be supported when they do their work on a different set ofsubstances such as plastics or wood.

Activity 2: Disappearing acts – the property of solubilityThis builds on the work you may have done with pupils in the Key Activity of Section 1,where pupils investigated unknown white powdery substances.

l Start by discussing what happens when you add something soluble like sugar toyour tea. How can you tell something has dissolved? Perhaps with older pupilsyou will use this as a chance to introduce terms like solvent (the hot liquid tea),solute (the sugar) and solution (the resulting sweet liquid).

l Give groups five different named substances and containers of water. Which ofthese substances are soluble in water? Ask them to make predictions and torecord the results of their investigation in the form of a table using words like‘slightly soluble’ and ‘readily soluble’. (See Key Resource: Using investigationsin the classroom.)

l Finally, ask each group to plan their own investigation of a different variable(something that can change) that might affect solubility of sugar in water. Think ofthings like temperature of liquid (solvent); granular size of sugar (solute), stirringor shaking the container. You might want to suggest pupils think how to presenttheir results as a graph. (See Resource 3: Lesson plan on solubility for moredetailed advice.)

3. Investigating irreversible changesHere, we build on the first two activities by now considering ways in which matter can bechanged. In science there are two types of changes pupils should consider:

l reversible changes – called physical changes;



l irreversible changes (changes that cannot easily be reversed) – called chemicalchanges.

Wax melting with heat and then solidifying again is a physical change. Dissolved sugarcan be regained if the liquid is evaporated, so this is also a physical change. (Resource 4:Disappearing ice cube race gives one idea for a classroom activity around a physicalchange.) But glass cannot be easily turned back into sand – so this is a chemical change.Case Study 3 shows one way that pupils can be challenged to think about chemicalchanges through a series of guided demonstrations. (See Key Resource: Usingexplaining and demonstrating to assist learning.)When iron and steel rust (a chemical change) the metal loses its shape and strength. Inthe Key Activity you use a competition to get your pupils thinking about how they couldslow down this chemical change.

Case Study 3: Showing irreversible changesSandile is an unqualified teacher volunteering in his rural village school. He believes thatlearning should be a combination of fun and seriousness. When the time comes to look atirreversible changes he sets up a series of activities.

First, he demonstrates what happens when a small cube of bread on the end of a wirepushed into a cork handle is toasted to a cinder over a flame. He asks his pupils to observecarefully. Eventually the bread gets dry enough to catch light and burn with a flame. Hethen asks: ‘When did it stop being bread?’ ‘What do you think has happened?’ ‘What solidsubstance are we left with if we grind the remains to a powder?’ Some of the pupils haveheard of carbon and Sandile explains this is what is left. He burns a small piece of woodand shows this, too, leaves carbon. He listens carefully to their answers and encouragesquestions based on their observations. In this way, he is able to assess their learning andthinking.

Next, he shows them a more obviously chemical change. He mixes tartaric acid powderand baking powder (sodium bicarbonate) and shows that no change happens. But then headds water and asks them to observe. This gave rise to lots of questions. Why all thefizzing and bubbling? What is in the bubbles? What gas is given off? Have the substanceschanged? If we evaporated the water what would we get? He talks about how newsubstances have been made. For more details see Resource 5: Molecules and atoms.

Sandile finishes the lesson by asking his pupils to each find three examples of chemicalchanges for tomorrow’s lesson. He is very pleased with the examples they give – some ofthe pupils even bring in materials to show how they have changed.

Key Activity: Slowing down an irreversible changeShow your class some metal articles that have rusted. Ask them: Where have they seenrust? What makes the iron or steel rust? What sort of change is this? Then tell them theirchallenge is to find out how to stop iron rusting.

Divide your class into groups. Give each group two iron nails (or other small pieces of iron)and tell them to clean the nails with sandpaper.

Then ask them to think how they will protect the iron from rusting. They should plan theirinvestigation; what they will do, the equipment they will need and make predictions. Why dothey think they have been given two nails?



The next day, ask the groups to set up their experiments. You will need to plan time for themto make observations over the next few weeks. After a few weeks, ask each group to reportback on their investigation. Was their method successful? Where might it be used?

Resource 1: Making a zigzag bookTeacher resource for planning or adapting to use with pupils

Adapted from: Stories into Books – D Dyer and A & V Kenyon (UCT 1990)

Resource 2: Looking at properties of solidsTeacher resource for planning or adapting to use with pupils

Many objects are made from solids. Solids come in many different types, each with theirown properties. The properties of the solid must be suitable for the object it is being usedto make.



One activity for your pupils is to brainstorm all the different properties materials can have.Put out a display of objects around the classroom. Make a label for each object with somequestions (see below for examples). Pupils, working in pairs, should spend 20 minuteslooking at the objects and answering the questions about the materials to help themdescribe their properties.Here are some suggestions for objects and labels for your display:

Object Label

Piece of copperwire

Pick up the wire. Can you bend it? Where have you seen it being used?What is able to pass through it?

Woven basket How does the basket feel? Can you easily pull it apart?

Metal spoon Pick up the spoon and think of three words to describe how it feels. Whathappens to the spoon if you put one end in a cup of very hot water?

Pottery cup Can you change the shape of the pottery? Would it break if you dropped it?(DO NOT TRY THIS.)

Piece of glass Can you see through the glass? What would happen if you dropped it? (DONOT TRY THIS.)

Plastic bag What happens if you drop water onto the plastic bag? Does it go through intothe bag? Can you easily fold up the bag?

Wooden spoon Can you bend the spoon? What happens to the spoon if you put one end in acup of very hot water?

Piece of cottonfabric

Hold the material up to your face. Can you see through it? What does it feellike?

Small magnet andpins

Move the magnet over the pins. What happens? Where have you seen amagnet being used?

As your pupils look at the objects you should move around the class talking to pupilsabout what they observe. At the end of the time, gather your pupils back together and askdifferent pupils to tell you what they observed about one of the objects. Build up a list ofproperties on your chalkboard or class wall. If your pupils aren’t familiar with theseproperty words in English, let them use them in their own language. You could put theEnglish words on a display in your classroom to help pupils learn them.This is an example list:

Strong

Hard

Tough

Rigid

Flexible

Transparent

Opaque

Melting point (high/low)

Insulator (heat and electricity)

Shatterproof

Magnetic

Conductor (heat and electricity)

Easy to cut

Expensive/cheap: Cost

Rough/Smooth

Waterproof



Make sure that your pupils can explain what each property means and ask them to draw atable in their books to show each property and an example of a material with that propertye.g.

Property What it means Example

Insulator Does not let heat gothrough it

Wood

Now set your pupils some problems around choosing materials. Here are someexamples:A: Nyasha grows vegetables close to her house but she needs some way of protectingher young plants from birds. What sort of structure might she build? What materialsshould she use? Why should she choose these materials?B: Sule wants to put a new top on the table in his kitchen; the old one is very uneven andcovered in burn marks. What sort of material should he use for the new table top?C: Akim needs a bag to carry his books to school. What sort of material should hechoose for the bag?For each problem, pupils should think about what the object needs to do, and choose,from their list, the properties it must have. Then they can choose which material would bebest in each case.

Resource 3: Lesson plan on solubilityTeacher resource for planning or adapting to use with pupils

Disappearing actsThis is one way that you can talk to your pupils about the idea of solubility.Think of a sweet like a strong mint or boiled fruit sweet. You put it into your mouth andenjoy the sweet pepperminty or fruity taste. But it doesn’t last forever. It gets thinner andsmaller and eventually it is all gone. Where did it go? Into the solution of sugar and salivayou have been swallowing while the sweet is in your mouth. Your liquid saliva has beengradually dissolving (the process) the solid sweet as you suck it. The result of thedissolving process is a solution of sugar and saliva.Perhaps you could have a competition in your class to see who can hold a soluble sweetin their mouth for the longest possible time. How did the winners do it?One little chew and the sweet breaks up into smaller pieces – you have lost! Swirl itaround in your mouth and you will have lost too! But if you can hold it in the cooler air onthe tip of your tongue, where there is also less saliva, you might just be a winner.Examples like this will give your pupils some ideas about the factors that affect solubility.Investigating solubility1. Each group of pupils chooses a factor around solubility to investigate. Some ideas are:

l temperature of the water (try hot, warm, room temperature and icy);l changing the size of the sugar pieces (try four lumps: one lump, one lump broken into

small pieces, one lump in grains and one lump which has been ground into powder);l stirring (try no stirs, slow stirring and fast stirring).



2. Put these questions on the chalkboard to help your pupils plan their investigations:

l What do you want to find out?l What do you predict will happen?l What equipment will you need?l What will you change each time?l What will you keep the same (to make sure the test is fair)?l What will you actually measure?

3. Make sure each group keeps all the other factors the same (constant). Only one factormust be different for each group. For example, if they are investigating stirring, they mustuse the same amount of water at the same temperature and the same amount of sugareach time.4. Ask your pupils to record their results in the form of a bar graph such as that below,which shows how many minutes it took for one spoonful of sugar to dissolve in the samevolume of water at different temperatures.

Background knowledge for the teacherModel of dissolvingThis is a clearer picture of what happens when solid matter dissolves in liquid. A solublesolid comes into contact with a liquid solvent. The liquid ‘unglues’ the particles of the solid,so they can move, mix in and slip freely between the particles of the liquid.The factors that affect the time it takes for a solid to dissolve are:

l temperature of solvent (faster in hot water);l size of solute (faster with small grains);l movement of solvent (stirring makes dissolving fast).



An example – dissolving saltThe teaspoon of salt is the solute. The water in the jar is the solvent. Once the salt isadded, the process is called dissolving. The product of dissolving is a saline (salty)solution.If more salt is added until no more will dissolve, we have a full or saturated solution.

Resource 4: Disappearing ice cube raceTeacher resource for planning or adapting to use with pupils

Organise your class into groups of four or five.1. For each group, choose someone to be an ‘independent observer’. This observer willreport:

l how well the group worked together;l exactly what the group did to solve the problem;l how long they took to do it.

2. Here is the challenge: Each group has a medium-sized ice cube in a polystyrene/plasticcup. Find the best way to make the ice cube disappear without a trace, not even a singledamp spot!3. The group observer records the results in a table like the one below on the chalkboard.4. Every minute, each group observer puts an ‘X’ if there is a trace of the ice cube left.5. Before the race begins, give pupils time to talk and plan how they will get the ice cube todisappear.Time: Mins

1 2 3 4 5 6 7 8 9 10 Actions Taken

A

B

C

D

E

F

Group6. Which group found ways to make their ice cube disappear the fastest? Who had thesecond best way? Which group was the least successful?7. Give the observers a chance to report back on how well each group worked together.They could use an assessment scheme like this one to score each group.

5

Excellent

Everyone participated actively. Everyone paid attention, made suggestions andhelped practically. Everyone co-operated well.



4

VeryGood

Most people participated and had a chance to do something to help. Everyone stayedinterested. No one felt left out.

3

Good

The group stayed together and got the work done. But some were a little quiet ordidn’t get given a chance to help.

1-2

Weak

The group was disorganised. One person took over. There was hardly any sharing ofideas and talk about what was happening.

Follow up the ice cube raceDiscuss the changes pupils saw as the ice cube disappeared. How does solid ice change(melt) to liquid water and eventually change (evaporate) into an invisible gas or vapour?These are called changes of phase. Finish the lesson by doing this quick quiz. Do thisquick quiz:

l List the things you can do to speed up the process of getting solid ice to change intoliquid water.

l What is the scientific term to describe the change from a solid to a liquid?l List the things that speed up the process of turning liquid water into a gas like water

vapour.l What word do we use for the change from a liquid to a gas?

Answer hints:Factors that affect melting and evaporation are:

l heat;l size and shape;l moving air;l pressure.

Pupils could write a short report on what they learned in the race for homework.

Resource 5: Molecules and atomsBackground information / subject knowledge for teacher



Original source: Primary Science, Developing Subject Knowledge, Jane Devereux

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Section 2: Exploring · PDF file · 2016-09-23l supported pupils as they carry out their own science investigations ... And if we don’t know – or can’t find out yet ... Make