Page 39 - 新思维科学教师用书7 试读样张

2 stAtes of mAtter
BACKGROUND KNOWLEDGE
Learners are likely to start with different
scientific backgrounds. Some will have a good
knowledge of the states of matter and their
properties. If your class is confident and has
covered this well at Stage 6, you will be able to
quickly work through the first topics. However,
be aware that, if your class has a mix of scientific
backgrounds, you will need to ensure they
all have the basic fundamental facts. Those
learners who have covered the topic in Stage 6
may well have ‘forgotten’ about it.
Matter occurs in three states: solid, liquid and gas.
They all have different properties. Solids have a
fixed shape and a fixed volume, and they cannot
be compressed. Liquids have a fixed volume,
but no fixed shape and can take the shape of
the container; they cannot be compressed.
Gases have no fixed shape or volume and can be
compressed. Gases and liquids can be poured,
but solids cannot.
Matter is made up of particles. The particles
in solids are arranged in regular rows with all
particles touching one another. The particles
cannot change places and can only vibrate.
Strong forces hold the particles together.
Because the particles cannot change places,
most solids cannot be compressed or change
their shape or volume.
TEACHING SKILLS FOCUS
Questioning 1
You could focus on active questioning for this
unit.
Most learners are comfortable with closed
questioning where the teacher chooses someone
to answer when they have raised their hand.
However, some learners can avoid taking part in
this.
To involve more learners you could use
mini-whiteboards, or paper that can be held
up, so you can see everyone’s response for
one or two word answers. You could also try
asking a question, leaving some thinking time
and then choosing someone to answer without
඀ࠡ JOEC
඀ࠡ JOEC
In liquids the particles are arranged so they are
touching one another, but they are not in a fixed
pattern. The particles can slide past one another
because the forces that hold them in place are
not very strong, so they can change shape,
but not volume, and cannot be compressed.
Liquids can be poured. The particles in gases
are spread out and can move freely. Sometimes
this means they collide with one another. There
are no forces holding the particles together –
this explains why gases can be compressed and
poured.
Matter can change its state from solid to liquid,
for example, when it is heated. The more energy
the particles have, the more they vibrate until
they can overcome the forces holding them in a
fixed place and the solid melts to become liquid.
Similarly liquids can become gases. The reverse is
true if energy is lost from the particles of a gas –
they cannot move around and so become a liquid.
These changes of state are what occur during the
water cycle.
For the rest of the unit – that covers atoms,
elements, the Periodic Table, compounds and
formulae, and compounds and mixtures – most
learners will have very little background knowledge.
This means that there will be less ‘catching up’ to
be done.
allowing learners to raise their hand. You could
use random name generators on the computer
or simply have each learner’s name on a piece
of card (or a lolly stick) placed in a beaker and
choose one at random.
Rather than ask closed questions with a one- or
two-word answer, work on developing more
open-ended questions. For example, rather than
Is this a solid, a liquid or a gas? ask:
Why do you think this is a solid a liquid or a gas?
How could you use the particle theory to explain
that?
How could you improve your understanding of …?
41