Context clues
WARM UP: READ ARTICLE AND FIND ONE NEW VOCABULARY WORD.
WRITE THE DEFINITION
Vocabulary
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Write a sentence for: fish screen and discharge water
What is a context clue?
Vocabulary
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
Write a sentence for:
phase changes
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Boiling point
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Freezing point
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Temperature
Step 1: go to sd27j.org
Step 2: Pick Stuart Middle School
Step 3: Staff- science- andrea lopez solorzano
Step 4: 6th grade tab, chemistry unit, resources, gizmo
Step 5: click enroll in a class: your username is
student id and then password is studen1
Step 6: Enrollment code:
Period 1:LCGCB2QMBW
Period 4: RY5MGDEELW
Period 5: E7TWGEUEJU
Period 6: J8NPWKRRAC
Vocabulary- now draw a picture
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Altitude – vertical distance, or elevation, above sea level.
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Boil – change from a liquid to a gas.
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Boiling point – the temperature at which boiling occurs.
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At sea level, the boiling point of water is 100 °C (212 °F).
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Water boils at lower temperatures at higher altitudes because air pressure is lower there.
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Freeze – change from a liquid to a solid.
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Freezing point – the temperature at which freezing occurs.
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At sea level, the freezing point of water is 0 °C (32 °F).
Gas – a phase in which matter has no definite shape or volume.
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A gas will expand to fill any container. A gas can also be compressed.
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Molecules in a gas are relatively far apart and move freely.
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Water in the gas phase is called water vapor.
Liquid – a phase in which matter has definite volume but no definite shape.
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A liquid will take the shape of a container but cannot expand or be compressed.
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Molecules in a liquid move randomly but stay close to one another.
Vocabulary continued
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Melt – change from a solid to a liquid.
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Melting point – the temperature at which melting occurs.
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At sea level, the melting point of ice is 0 °C (32 °F).
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Phase – a state of matter with certain physical properties.
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Solid, liquid, and gas phases occur naturally on Earth.
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Plasma is a phase found in stars.
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Solid – a phase in which matter has a definite shape and a definite volume.
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A solid will retain the same shape and volume in any container.
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Atoms in a solid are held in a rigid structure and cannot move freely.
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Water in the solid phase is called ice.
Discussion questions
As students are working
or just after they are done, discuss the following questions:
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What are some of the differences between solids, liquids, and
gases?
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How does temperature relate to molecular motion?
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What causes materials to change phase?
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Why does the temperature stay constant during a phase change?
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Why do water pipes burst in the winter?
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Why does it take longer to cook pasta at high altitudes than at sea
level?
Complete worksheets A,B,C
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Follow step by step directions on worksheets. Then do the assesment
Worksheet A
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Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
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A family from Minnesota turns off the heat and flies to Florida for a winter
holiday. When they come home, all of their water pipes have burst. What do
you think happened?
_________________________________________________________________________
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Spaghetti takes about 9 minutes to cook at sea level, but about 14 minutes in
the mountains. Why do you think this is so?
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_________________________________________________________________________
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_________________________________________________________________________
Worksheet A continued
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In the Phase Changes Gizmo™, select the Micro view and set the Ice
volume to 50 cc. Click Play ( ) and observe molecules in the solid (ice),
liquid (water), and gas (air) phases.
In which phase(s) are the molecules held rigidly together?
 ______________________________________________
 In which phase(s) do the molecules move freely?
 ______________________________________________
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In which phase(s) are the molecules held in a defined shape?
________________________
 In which phase(s) do the molecules take the shape of their container?
_________________
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Solid
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atoms or molecules held in a rigid structure. Atoms in the structure
may vibrate, but do not move freely
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A solid has a definite shape and a definite volume
Liquid
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molecules that are attracted to one another but can still move
around so that they take the shape of their container. ‘
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Liquids thus have a definite volume but an indefinite shape.
gas
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rapidly moving molecules that move and collide freely.
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A gas will expand to occupy all the space in its container.
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Gases also can be compressed to a very small volume.
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Thus gases do not have a definite shape or volume
Solid, liquid, gas
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When a solid is heated, the atoms begin to vibrate more and more rapidly. Eventually
the vibrations are strong enough to break the rigid bonds holding the atoms together,
and the solid melts into a liquid. During the melting process, temperature does not
increase because the added heat energy goes into melting the solid rather than
heating the liquid.
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In a liquid, the molecules move at a variety of speeds. The fastest-moving molecules
can escape the surface of the liquid and become a gas. This process is called
evaporation. As the liquid is heated, the average speed of the molecules increases
until large bubbles of gas form within the liquid. This is boiling. The temperature
remains constant during boiling because the fastest molecules are constantly leaving
the liquid and escaping as gas.
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Cooling produces the opposite phase changes. As a gas is cooled, the molecules
slow down until their mutual attraction causes them to clump together and form
droplets of liquid. This is condensation. When a liquid is cooled, the molecules move
slowly enough that they can begin to form rigid chemical bonds in a crystalline
lattice. This is freezing