Grade 3: Structures and Mechanisms: Stability |
Achievement
Level
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Overall Expectations
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1
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2
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3
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4
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•demonstrate an understanding of the factors that affect
the stability of objects; |
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•design and make structures that include mechanisms and
that can support and move a load, and investigate the forces acting on
them; |
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•describe, using their observations, systems involving
mechanisms and structures, and explain how these systems meet specific
needs and how they have been made. |
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Specific Expectations
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Understanding Basic Concepts |
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•describe, using their observations, ways in which the
strength of different materials can be altered (e.g., folding increases
the strength of paper); |
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•describe ways in which forces alter the shape or strength
of different structures (e.g., a load may cause a cardboard box to buckle); |
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•describe ways to improve the strength and stability
of a frame structure (e.g., use of triangulation or a cross-member); |
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•describe, using their observations, the role of struts
(e.g., to resist compression) and ties (e.g., to resist tension) in structures
under load (e.g., describe the effect of adding a strut to a wooden frame); |
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•describe, using their observations, the changes in the
amount of effort needed to lift a specific load with a lever when the position
of the fulcrum is changed; |
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•describe, using their observations, how simple levers
amplify or reduce movement (e.g., in operating the limbs of a puppet); |
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•describe the effects of different forces on specific
structures and mechanisms (e.g., a structure collapses when the load is
too heavy; a latch on a gate opens when pressed). |
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Developing Skills of Inquiry, Design, and Communication |
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•ask questions about and identify needs and problems
related to structures and mechanisms in their immediate environment, and
explore possible answers and solutions (e.g., investigate the effects of
folding on the shape and strength of materials); |
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•plan investigations to answer some of these questions
or solve some of these problems, and explain the steps involved; |
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•use appropriate vocabulary to describe their investigations,
explorations, and observations (e.g., use terms such as fulcrum, load,
and effort when describing levers); |
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•record relevant observations, findings, and measurements,
using written language, drawings, charts, and graphs (e.g., record the
modifications they have made to increase the stability and strength of
their structures); |
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•communicate the procedures and results of investigations
for specific purposes and to specific audiences, using demonstrations,
drawings, simple media works, and oral and written descriptions (e.g.,
make a mobile that illustrates their discoveries about balance); |
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•design and make a stable structure that will support
a given mass and perform a specific function (e.g., a bridge, a photo frame); |
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•use appropriate materials to strengthen and stabilize
structures that they have designed and made and that are intended to support
a load (e.g., use gussets, struts, ties, buttresses); |
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•design and make a levered mechanism (e.g., a model of
an animal whose legs are moved with a lever); |
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•design and make a stable structure that contains a mechanism
and performs a function that meets a specific need (e.g., a drawbridge,
a crane); |
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•use appropriate equipment and adhesives when making
structures that they have designed themselves (e.g., transparent tape for
paper; low-temperature glue gun for wood); |
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•use hand tools (e.g., hand saws, scissors) and equipment
(e.g., templates, mitre boxes) appropriately to cut a variety of materials
(e.g., wood, paper, cardboard, plastic). |
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Relating Science and Technology to the World Outside
the School |
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•distinguish between the structure of an object (e.g.,
the chassis of a vehicle) and its mechanical parts (e.g., the wheels and
axles); |
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•recognize that geometrical patterns in a structure contribute
to the strength and stability of that structure (e.g., a climbing frame); |
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•demonstrate awareness that the strength in structures
is due to bulk (or mass), number of layers (e.g., layers in particle board),
and shape (e.g., triangulation); |
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•identify a number of common levers (e.g., crowbars,
scissors, hammers, pliers, wheelbarrows, tweezers, tongs) and describe
how they make work easier; |
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•identify efficient ways of joining the components of
a mechanical structure or system (e.g., construct a right-angled corner;
use an axle at a right angle to the frame); |
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•describe, using their observations, how different balance
points of different masses affect the stability of a structure; |
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•predict which body positions provide the most stability
in various circumstances (e.g., standing with legs apart, lying on the
ground). |
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Student Name: |
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