38

Materials

Grade5, Unit 5M.2:

Materials

Unit 5M.2: Making Things by

Changing Materials

Different kinds of materials

Changing materials in the

kitchen

Science skills:

Classifying

Observing

Communicating

By the end of this unit you should:

Define melting and freezing.

Identify temporary and permanent change.

Classify the changes.

Give examples for each type of change.

39

Materials

Grade5, Unit 5M.2:

Materials

Different kinds of materials

Classify materials according to the properties of the material.

Write your results in the shown table.

Materials

Edib

le

Ine

dib

le

Natu

ral

Synt

hetic

Meta

ls

Non

-meta

ls

Flexib

le

Britt

le

5.10.1 – 5.10.3

40

Materials

Grade5, Unit 5M.2:

Materials

Materials

Edible

Ine

dib

le

Natu

ral

Synt

hetic

Meta

ls

Non

-meta

ls

Flexible

Britt

le

Materials are classified according to their properties, for

example:

1. Materials that are edible and those that are not.

2. Materials that are natural and those that are synthetic.

41

Materials

Grade5, Unit 5M.2:

Materials

3. Materials that are metals and non-metals.

4. Materials that are flexible and those that are brittle.

Changing States

Solids melt when they are heated to form a liquid.

If we heat an ice cube, it will change into liquid water.

Liquids freeze when cooled to form a solid.

The ice will change back into liquid if we heat it.

The freezing and thawing of water is an example of a

reversible change or Physical change

Physical change: the substance changes without producing any

new substance. (REVERSIBLE CHANAGES)

Heating

Freezing

Evaporation

Condensation

42

Materials

Grade5, Unit 5M.2:

Materials

Activity (1):

1. Take a ball of clay, make a shape.

2. Can you change it back to a ball ? __________

3. Is there any new matter formed? __________

Activity (2):

1- Put a small piece of chocolate in a spoon and put it over

steaming hot water .

2- What do you observe?

____________________________

3- Can you turn it back into a piece of chocolate again? ______

4- How? _________________________________________

Examples of temporary change

Melting ice cream Cutting bread Melting candle

When the wax gets hot it melts and

turns into a liquid. When the wax

cools it turns back into a solid.

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Materials

Grade5, Unit 5M.2:

Materials

If we heat a raw egg it will change into a cooked egg.

Putting it in the freezer will not change it back into a raw

egg. Cooking eggs results a chemical change.

In a chemical change, materials turn into a new and

different material.

The new material cannot be changed back into what it was

before.

Examples of chemical changes:

Burning Paper

Chemical change: The substance turns into a completely

new material.

Liquid HEAT

Solid

Cooking

44

Materials

Grade5, Unit 5M.2:

Materials

Activity (3):

1-Add tea spoon of baking powder to 100 ml of vinegar in

the beaker.

2-What do you observe?

------------------------------

Describe the material

before mixing two materials

Describe the material

after mixing two materials

----------------------

----------------------

---------------------

---------------------

3- What kind of change happened? --------------

Why? -------------------------------------

Activity 4:

1- Burn a piece of a magnesium strip.

2-What do you observe? ----------------------

Properties of material

before burning

Properties of material

after burning

---------------------- ---------------------

3- What kind of change happened?____________________

Why?_______________________________________

45

Materials

Grade5, Unit 5M.2:

Materials

Changing Materials in the kitchen

Materials changes can be considered as temporary (Physical)

(i.e. the substance has just changed its appearance or can be

easily changed back) or permanent (Chemical) (i.e. the

substance is permanently changed to something new).

5.10.5

Activity 1:

Dissolve some salt in a little water.

Leave the cup on a windowsill and look at

it each day.

What do you observe?

-------------------------------

Activity 2:

1. Mix (flour + yeast +water) in a bowl.

2. Bake them in the oven.

3. What do you observe? -------------

4. Can you turn the bread back to the ingredients it was

made of? --------------

Why? --------------------------------

46

Materials

Grade5, Unit 5M.2:

Materials

Activity 3: Frying an egg

Note the changes that happen when the egg cooks

1- What do you observe?

--------------------------------------

2- What kind of change happened? --------------

Why? --------------------------------------

Activity 4: Making paper

Making a wet pulp from waste paper (e.g. newspaper) and

blend it in a kitchen blender until it is smooth and then

laying the paper in a tub or frame. Ink or dye can be

added to give the paper a color.

Note the changes that happen.

1- What do you observe?

_________________________

_________________________

2- What kind of change happened? ________________

Why? _____________________________________

47

Materials

Grade5, Unit 5M.2:

Materials

Test Yourself!

Classify the changes in the following pictures into permanent

or temporary changes.

----------------------------------------------------------

-------------------------------------------------------

----------------------------------------------------------

-------------------------------------------------------

------------------------------------------------------

-------------------------------------------------------

Cutting paper

paper

Cutting wood

wood

Cutting hair Baking cake

Breakfast tray Burning house

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Materials

Grade5, Unit 5M.2:

Materials

Do you know?

Permanent changes are very useful. We would not be able to

eat bread if it went back to flour!

Mugs would be completely useless if they turned back into

clay when they got wet.

Key idea:

Melting: Changing solid into liquid.

Freezing: Changing liquid into solid.

Physical change = Temporary change = reversible: The

substance changes without producing any new

substances it can change back to how it was before.

Chemical change = permanent = irreversible: The

substance turns into a new material it cannot change

back to the way it was.

?

49

Materials

Grade5, Unit 5M.2:

Materials

Project:

As an experiment, do these activities

and write your result in the report

paper.(put more details about what

they have to write- hints or details

to help them to write the report)

- Making a lemon juice drink

- Making and testing clay bricks

- Making a rope out of used

polythene bags.

-

Key questions:

1. What will happen to the paper if you burn it?

……………………………………………………………………………………………………………

2. Write the type of change :

Nail rust ……………………….…… Frying chips …………………………

3. Give reason:

Burning fuel is a permanent change

…………………………………………………………………….………………………………………

Melting butter is a reversible change

…………………………………………………………………………………………………………..

Key words:

Chemical

Physical

Temporary

Permanent

Reversible

Irreversible

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Materials

Grade5, Unit 5M.2:

Materials

Changing Materials

Here we are going to look at changing materials to make

them more useful for our needs!

Making newspaper stronger

Test the strength of a sheet of newspaper,

by putting some heavy science books in the

middle and trying to lift them!

What happened?

Now think of way, using the same newspaper to make it

strong enough to lift the book.(try folding!)

Making a rope out of used polythene bags

You have a challenge – make the strongest piece of rope

not less than 1 m long, from five standard polythene

bags. Your teacher will test the rope and see how much

weight it can carry. Let’s see who wins!

Making and testing concrete – TEACHER Demonstration.

Concrete is made from a mixture of cement, fine sand and

water. Your teacher will mix and make it for you – with some

of you helping.

Bring a small box that you will fill it with the concrete – and

the leave to dry somewhere outside, once it is dry you can rip

the box off and you will have a small block!

After Each Experiment ask

yourself:

What has changed?

What kind of change is?

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Materials

Grade5, Unit 5M.2:

Materials

HEATING: REVERSIBLE OR NON-REVERSIBLE

CHANGES?

The experiment was set

as shown, complete the

table below!

foil dish

sand

sand tray

tea light

stand

Material

PREDICTION

Will the

change be

REVERSIBLE?

DESCRIPTION

BEFORE HEATING

DESCRIPTION

AFTER

HEATING

Allow it to

cool.

Was the

change

REVERSIBLE?

chocolate

butter

wax

cheese

egg

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Materials

Grade5, Unit 5M.2:

Materials

Key questions

A flow chart can show how common things are made. This

flow chart shows how newspaper is made from wood. Make

flow charts to show the following processes.

How a concrete block is made?

....................................................................

How a fried egg is made?

....................................................................

How a loaf of bread is made?

....................................................................

How a cup is made from clay?

....................................................................