unit 5m.2: making things by changing materialsoct 05, 2011 · grade5, unit 5m.239 materials :...
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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?
....................................................................
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