SOLIDS
Let’s grow a solid
Supports National Curriculum, Key Stages 1 and 2, Units 4D, 5C and 5D
Suitable for years 4, 5 and 6.
The time for the session is approximately 1 hour. The length of the session can be varied
by modifying the PowerPoint presentation once downloaded.
Outline of content
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Establish what the children already know, using a demonstration
Explain differences between solids and liquids
(Different materials change from liquid to solid at different temperatures)
Solids remember how they grew
There are two types of frozen water, formed in different ways: a) snow and b) ice
a) Formation of snowflakes using an on-line computer simulation
b) Formation of (close packed) crystalline solids using a game and bubble rafts
Bubbles are very different to either water or air because they are a sandwich
Special solids can be grown using MB (Molecular Beam Epitaxy) which are used
in computer chips etc.
Points to note:
Please read the notes about risks and agree the assessment with the
teacher before the session!
Cross References
 The slides in the PowerPoint presentation are referenced in the plan.
 As the presentation may be running throughout the session some simple slides
provide a suitable background, alternatively switch to a black screen
 Apparatus details are below the table and are linked to the relevant sections.
 Risk assessments are below the table
 Vocabulary: The presentation uses expressions included in the KS 1&2 strategies
http://www.standards.dfes.gov.uk/schemes2/science/?view=get
 (NB It also uses terms not introduced until KS 3.)
Misconceptions to be corrected
 Crystal surfaces are not formed naturally
 Ice, snow and water are different materials
 Solids such as crystals cannot be melted
 Freezing and melting are not reversible
 Children often confuse melting and dissolving. This presentation explains
melting.
Let’s Grow a Solid
The children can take advantage of a ‘live’ demonstration by asking lots of questions –
please use the ‘discussion’ notes to encourage them to do this!
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Activity
Discussion
Aims/Facts
Slide 1. Start by an activity to
attract their attention.
Use a spray bottle to spray
water onto a cloth that changes
shade of colour when it is wet.
Then try to spray using the
bottle containing the ice.
(apparatus list for activity 1.)
Ask them what changes they see.
Encourage answers about liquids
being able to change shape so is
squeezed out of the spray.
Aim to find out what
they know and to
establish the
difference between
liquids and solids..
Use slide 2 to reinforce that
solids do not change shape
when you move them.
The natural object is Stannage
Edge in Derbyshire, a natural
rock formation.
The crown links well with
crystals shown later in the
presentation.
Show a melted candle or piece
of chocolate.
(apparatus list for activity 3.)
Use slide 3 to reinforce that
liquids have no shape. The
atoms in the liquid can move
around freely.
Talk about atoms being very
tiny particles.
Tell that solids are amazing
because they ‘remember’ how
they grew. Slide 4
Eg as water freezes it can form
2 types of solid –snow/frost and
ice
Show two glasses of water and
explain that one is water from
the tap and the other from
melted ice. Ask whether they
Ask what is different. Encourage
statements about solids not
changing shape therefore it is not
possible for the ice to be sprayed
from the bottle.
There are numerous different sorts Solids have a fixed
of solids.
shape.
(Be prepared for questions about
paper or springs which are
flexible and solid.
Solids can be forced to change
shape.)
Ask what happens when they keep
chocolate in their pocket on a hot
day. Use this to lead into a
discussion about melting being
the change from a solid to a
liquid. (Different solids melt at
different temperatures. Ice melts
at 0oC, iron at 1535oC.)
Liquids take the shape
of the container. A
solid melts to form a
liquid.
Ask them whether they have seen
frost on car windscreens on frosty
mornings and icicles etc
Use slides 5 and 6 to encourage
the children to recount what they
have seen and link the solids with
water.
Discuss how the water in each is
formed. The melted ice was solid
before it melted. The water from
the tap was rain so formed from
The same material can
exist as both solid and
liquid.
Liquids do not have a
memory of how they
are formed.
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can tell the difference. Slide 7
Explain that during the session
they will learn about two ways
solids grow. Slide 8
Type 1 Slide 9 Snow flakes
The atoms add on exactly
where they hit. Slide 10
Computer simulation
(slide, 11, 12 )
(Arrange in advance with the
teacher that the site can be
reached easily during the
presentation the school may
have to load java.) Show the
molecules adding slowly at first
so they see the molecules
adding one by one. Then let
them watch the fractal pattern
building until there are about
100 molecules. Point out that it
is not much like a snowflake.
So add more. It begins to look
like a flake when 10 000
molecules are in the flake. You
can often minimise this
program and then return to it at
the end of the session to see
how big it has grown. Note the
easiest way to find the site is to
put ‘DLA apricot’ into google –
Show slide 13
Type 2, ice
Slide 15
Emphasise that ice is hard.
Slide 16 Explain that this is
because of the way the ice was
formed from water.
10. Slide 17 Explain that the
crystals have atoms in layersthat just as they have learned
that atoms are very small- the
condensed water vapour.
This is useful because scientists
can grow solids atom by atom in
special ways to do special tasks.
Talk about the formation of
clouds - that water vapour rises
and forms clouds. When it is cold
the water vapour freezes.
Snowflakes grow as water
molecules add onto others.
Discuss the huge number of
molecules in a flake. The pattern
produced on the site is a fractal.
Ask how they make snowballs.
They will talk about squeezing the
snow. Bring out that there are a
lot of spaces in the snow.
Ask whether they have ever
jumped on a frozen puddle. Ask
what the flakes of ice are like:
hard, see-through, sharp edges,
flat sides. Ask them if they have
ever felt under the ice from a
puddle and noticed how very
smooth it is. Compare with the
pictures of crystals. Slide 16
They are impressed by the large
numbers. Explain that in the large
piece of quartz crystal shown
there will be 100 million layers!
Liquids can be
changed to a solid by
cooling and this is
freezing or
solidifying.
Snowflakes are made
of many thousands of
ice molecules.
Solids formed in this
way have spaces in
them.
Solids formed in this
way have very smooth
sides and are very
hard.
The layers of atoms
are very, very thin.
layers are very thin. About
10,000 layers are needed to get
the thickness of a piece of
paper.
11. Slide 18,19 Growing solids
atom by atom artificially.
The temperature has to be just
correct to get the best structure.
A beam of atoms is sprayed
onto a surface and they move
around to find the closest
position
12. On an Overhead projector,
show discs being packed as
close as possible together.
(apparatus list for activity 11)
Explain that when they are
packed closely they form a
solid – crystal. Slide 19
13. Class group activity.
(apparatus list for activity12)
Hand out about 12 discs per
group. Ask them to place them
together so that they are as
close as possible. Do this on the
OHP at the same time. Give
them three narrow strips of
paper and ask them to place
them over the lines they can
see. Use slides 21,22,23, 24 to
reinforce this.
14. Bubble rafts- slide 25
(apparatus list for activity 13)
Explain that we can find out
more using bubbles. Go
through the instructions with
them using slide 26. Explain
that they will need to be very
sensible if this is to work
because if they do not do it
very carefully they will not get
Discuss crystal growing kits
Different solids melt
(available from toy shops). Ask if at different
they have ever grown crystalstemperatures.
they would have warmed the
powder in the water and then
leaved it to cool. Explain that just
at the temperature where a liquid
changes to a solid, the atoms can
move around to find the best place
so that they are all very close
together. Show the BBC clip to
show that some VERY big
crystals can grow – if you leave
them long enough!
When the discs all
touch each near discthere is only one
possible pattern.
They may suggest other structures
but this is the closest packed and
known as ‘close packed
hexagonal’. Ask if they know the
word hexagonal- some may link
this with a hexagon. Talk about
the six sides and point out that
each disc touches six others.
Atoms in a solid
(crystal) are in a
pattern which repeats
many, many times.
The children will see that the
pattern formed by the bubbles is
similar to that formed in the
previous exercise. They should
slide the bubbles around carefully
with their fingers to form a large
raft.
Safety: If they ask can they do it at
home, warn them to ask an adult
to make the hole in the yogurt pot
The atoms move so
that they are packed
closely in the pattern.
Such solids are hard.
the effect.
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as it is difficult to push the pin
through.
Show slide 27 and ask what
In the discussion compare with
they can see. Use slide 28to
other natural structures. Ask
emphasise that the bubbles
where they have seen similar
slide around to reach the best
patterns and show the picture of
place. If a bubble bursts others the honeycomb - if available, take
will move so there is no gap.
in a piece of honeycomb to show
Use slides 29 and 30 to show
them.
the rows clearly.
Slide 30
Discuss the bubbles. They are
They will mention bubble bathsnot like the soapy water, nor
task if they have been in a jacuzzi
the air. The layers of bubbles
in the swimming baths- ask what
could be built up to form a
would happen if bubble bath
structure that is very different
liquid were to be put into a
to either the water or the air.
jacuzzi. This emphasises that the
Show slide 32, then the picture structure of the water is different
of the foam dance.
to that of air or water.
Slide 33 Reinforce that soap
Talk about foam from soapy
films are very thin.
water. Bring out in the discussion
A thin film of water is very
that the bubbles will build
different from water in a bucket something that cannot be made
or glass.
from just water or just air.
We have a very thin sandwich
‘air- water –air’.
The bubbles behave like layers
of atoms – which can build a
crystal.
Sandwich crystals can be made Ask if they can spot some of them
with the very special machine.
on slide 35?
Slide 35 These have different
iPods, games consoles, play
sorts of atoms in layers. These
stations, mobile phones etc all
can do very special jobs.
need these special crystals.
They make it possible for very
Explain that computer ‘chips’
complicated electrical circuits to
are made from these very
be made that take up very little
special crystals.
space.
‘Chips’ are used in lots of
different items that they use.
Re-cap session
Slide 37
Finish off saying scientists do
Explain that early computers took
amazing things.
up a large room which was filled
Maybe leave them with some
with racks of equipment These
saturated salt solution and tell
computers could do about the
them that if the water
same as a ‘calculator’.
evaporates very slowly they
Then asked whether iPods made
will get bigger crystals.
by the same technology be any
The close packed
pattern formed by the
atoms occurs many
times in nature.
The bubbles behave
like atoms building a
solid.
Artificial crystals are
used to make
computer ‘chips’
which have numerous
everyday uses.
Revise
Scientists find out
things and make new
amazing things
possible.
Explain that scientists
find answers to
questions.
Slide 38
use – as they would take up
several rooms!
They should keep
asking questions.
IMPORTANT NOTES ABOUT HAZARDS AND RISKS
Water is used in the first demonstration because both the solid and liquid forms can be
handled safely by the children. The original contents of the spray bottles are NOT
suitable, so the bottles and spray heads must be washed thoroughly.
For the activity with counters or washers etc, the items used should not be so small that
they might be swallowed. Washers are good because they have a hole in the centre which
would allow air through if swallowed. Pennies are so familiar they unlikely to be tasted.
The bubble raft experiment uses washing up liquid which is safe for hands.
Care should be taken to ensure that the water is not spilled on the floor causing a child to
slip.
If the children suggest that they would like to make bubble rafts in the bath, they should
be warned that an adult should make the hole in the bottom of the yogurt pot.
APPARATUS
A data projector and white board/screen to show power point slides are required as well
as an overhead projector. It is helpful if the overhead projector can be used at the same
time as the power point slides.
Before the session connect to the website
http://apricot.polyu.edu.hk/~lam/dla/dla.html ready for the computer simulation in
activity 7. Arrange in advance that the webpage can be downloaded and that the applet
will run.If you use Goggle to search for ‘DLA apricot’ then the website comes up as
nmber1.
The simulation shows fractals growing and has the options- Grow, Pause, Resume, Reset
and Grow slowly. Practice before the session. It helps to start by showing the fractal
growing slowly at first so the children see the particles adding slowly. Then explain that a
snowflake has many, many more particles and show the quicker rate of growth. Stop it a
few times to discuss whether there is sufficient detail for the structure to look like a
snowflake.
Activity 1
 2 empty spray bottles of the sort for cleaning materials – well washed out.
 Half fill with water
 Bubble pack or other heat insulation material
Unscrew the top of one and squeeze some air out. Tighten the top and place the bottle in
a freezer. Before the presentation, remove the bottle of ice from the freezer and insulate it
with several layers of bubble pack or other good heat insulator to prevent the ice melting
before the presentation.
Activity 3
Optional items to help to explain melting:
Melted candle,
soft chocolate
piece of pumice stone
Other items to help later explanations if available
 crystals
 honeycomb
Activity 5
Two transparent tumblers
1. containing water which is melted ice and
2. containing tap water.
Activities 12 and 13
Demonstration
 Overhead projector (OHP)
 3 narrow strips of paper (about 15 cm x 0.3 cm)
 Discs to represent atoms
o These could be washers about 1cm in diameter
or transparent discs, pennies, ‘tiddlywinks’, buttons etc
o They must all be the same size.
o Washers or transparent discs allow the strips of paper to be seen clearly
during the demonstration on the OHP
o Pennies are easily obtained for class use.
Linked class activity
 small bags containing about 12 discs – one bag per group of children
 3 thin strips of paper or coloured plastic per group
Activity 14
Bubble rafts
 washing up liquid
 teaspoon
 water
 yogurt pots – 1 per group of children
 large bowl – 1 per group of 3 or 4 children
[eg. washing up bowls, large ice-cream tubs (at least 3 litres), etc ]
 Paper towels – for mopping up
Before arriving at the school make a small pin hole in the centre of the base of each
yogurt pot. (Note: the hole should be made in advance because it is difficult to push the
pin through. The hole should be as small as possible so that the bubbles are small. )
Before the session fill the bowls to a depth of about 8cm.
The detergent must be added very slowly to the water (NOT the water to the detergent) so
no bubbles are formed. It is best to do this in advance and hand the bowls round at the
appropriate time.
The water must be deep enough for the base of the up-turned yogurt pot to be below the
surface of the water. If shallow containers are used then a small fromage-fraise pot is
better.
Once the air trapped air has left the yogurt pot, a child can lift it carefully and put it back
in the water to form more bubbles from the trapped air.
The children should guide the bubbles with their hands so they see them form a single
layer and move to become close packed (anneal).