MI BIG
Matter and Energy IV.1
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(Inspiration)
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All students will measure and describe the things around us.
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All students will explain what the world around us is made of.
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All students will identify and describe forms of energy.
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All students will explain how electricity (and magnetism) interact with
matter.
Overview
The world, as we know it, is the result of the interaction between matter
and energy. This interaction results in the changes that we see all around
us. Every time a light bulb is turned on people witness that interaction.
The study of matter and energy encompasses a large number of engaging and
challenging concepts. At the elementary level students build the
foundation for learning about matter and energy by becoming familiar with
different properties of matter. By high school, students will understand
many different forms of matter as well as energy.
Essential Background Narrative
Measure and describe the things around us.
Explain what the world around us is made of.
Identify and describe forms of energy.
Explain how electricity (and magnetism) interact with matter.
Elementary school children should be able to describe attributes of
matter, which are qualitative, such as color, smell, size, and texture.
Other attributes of matter are magnetic properties, such as attract and
repel and density determined by sinking and floating. As students get more
experience with qualitative aspects, they can move to quantitative
attributes such as mass, weight, volume, and length. Students often have
difficulty understanding the concept of matter. Research suggests that
children often think that everything that exists is matter, including
heat, light and electricity. They may also think that matter does not
include liquids and gases.
Mass and weight are two different ways to measure matter. Mass is a
measure of the amount of matter in an object and a measure of the amount
of inertia an object has. Mass does not change. Weight is dependent on
location and can vary depending on where it is measured. Weight will be
less if you are on the moon compared to the earth. Some students are
confused about the difference between mass and weight. Mass is a property
of all matter, weight depends on gravity. If there is no gravity, there
can be no weight.
Accepting weight as an intrinsic property of matter is difficult for some
students. It is interesting to note that many sixth and seventh grade
students still appear to think of weight as "felt weight". This
leads them to think that if they cannot feel the weight then matter has no
weight at all.
Volume is another way to measure matter. Volume measures the amount of
space an object occupies. Two objects can have the same mass, but very
different volumes. Students frequently confuse mass and volume thinking
that they describe the "amount of matter" and therefore are the
same.
Elementary students are often asked to identify floating and sinking
objects. This poses problems for elementary students who misunderstand why
objects sink or float. Density and buoyancy are complex ideas for students
and are difficult to understand and teach at the elementary level. It is
important to know that some students will think that objects sink in water
because they are heavier than water. They also may think that objects
float because they have air in them. In order to really understand
floating and sinking, students must understand density. Objects sink if
they are denser than the liquid and float if they are less dense than the
liquid. Freighters are an excellent example of sinking and floating to
begin to challenge students' ideas. Freighters are huge steel ships that
are very heavy. Just the paint used to protect them can weigh tons. Yet
large ships float because they displace their weight in water.
Density is a ratio of mass to volume and is, therefore, a derived
quantity. Density is a property of matter that does not change, regardless
of the size of the sample. However, the density of an object can be
altered by increasing or decreasing the volume of the object, while
keeping the mass constant. For example, a hot air balloon rises when the
air inside the balloon is heated because the process of heating causes the
volume of air inside the balloon to increase and the density to decrease.
Interestingly, students often confuse density and thickness, assuming that
thick liquid is denser than thinner, less viscous liquids. Simple
experiences with everyday objects can make it clear that this is not true.
Oil is much thicker, more viscous, than water and yet is less dense than
water. The thickness of a liquid is related to the strength of the
intermolecular forces rather than spacing between molecules
Measurement is an important skill that students begin developing in the
earliest years. It begins with non-standard units of length, volume, and
mass. An important concept is that any measurement is an estimation to the
nearest unit being used. The measurement tool and the unit will be
determined by the attribute being measured and the purpose of the
measurement. Students must be able to select and use a balance to measure
mass and measuring cups or graduated cylinders for volume. When measuring
matter, students should understand that all measurements have error
because one must always estimate the last reported digit. When measuring,
a person must estimate one more place than the last number on the
measuring device. All instruments have limitations on their ability to
measure.
Importantly, students in the middle school should be able to explain and
use appropriate measurements to describe the properties of an object or
substance. For example, they need to be able to determine if they should
use mass or weight when finding density and they need to know when to use
area and volume.
Beginning in the elementary years, students should be able to identify the
properties of materials that make them useful. This can be tied to simple
ideas like strength or stretching and to more complex ideas like the
conduction of heat and electricity. In the high school years, students are
asked to analyze properties of common household and agricultural materials
for risks and benefits.
Using terms such as element, compounds and mixtures require understanding
of the smaller particles of matter. Students at the elementary school
level have difficulty imagining the atomic level of substances. Therefore,
there are no elementary level benchmarks for this standard.
In the middle school years, students should describe matter in terms of
its molecular and atomic make-up. In particular, students should begin
with those materials with which they are familiar. Copper, iron, salt and
sugar are among the examples.
Individual atoms are composed of the same particles; protons, electrons,
and neutrons. An atom is the smallest part of the element that would have
all the properties of that element. Atoms can bond together with other
atoms to form molecules. That is why we have such a myriad of substances,
even though there are only 92 naturally occurring elements. Who we are and
how healthy we are is the result of the way atoms and other substances
interact with one another within our body. Color and hardness are examples
of two properties determined by the way atoms interact.
Students at the middle school level are asked to describe the arrangement
and motion of molecules in solids, liquids and gases. When asked to
consider arrangement of molecules in a solid, liquid or gas, students
often overestimate the differences in space between particles. The space
between particles in a solid, liquid, or gas is not as big as students
tend to think. The density difference is actually very small.
Molecular motion is also a problem for students. For example, they often
think that molecules of a gas "just float". Rather, gas
particles are in constant motion. Students also think that gas is not
matter because it is invisible. As suggested above students think that gas
particles float while they are sure that particles in a solid have no
motion. This is true only at absolute zero. Temperature measures the
average kinetic energy of the molecules. A gas and a solid at the same
temperature have the same average kinetic energy. The speed of the
molecules depends on their molecular mass. They also do not account for
the empty space between molecules. The space between molecules of a solid,
liquid, or gas is empty. There is no dust or air between the particles.
There is only one benchmark for this standard. The middle school and high
school benchmarks are in other strands. At the elementary school level,
students are asked to identify heat, light, sound, food energy and energy
of motion for specific phenomenon. For example, students might notice that
water is heated by the sun, and music comes from a piano. At this level,
it would be important to begin talking about energy as an abstraction, not
as a thing. Energy has no mass and takes up no space so it is not matter.
Also, students believe energy is associated only with humans or movement,
is a fuel like quantity that is used up, or is something that makes things
happen and is expended in the process.
All students should know safety precautions about electricity. Beginning
in the third and fourth grade, students should be constructing simple and
useful electrical circuits. They should be able to understand how a
flashlight works. In the middle school, the building of simple circuits is
explained in terms of flow of current. Students also move beyond looking
at battery powered toys to explaining how electrical devices such as
radios and stereo systems work using appropriate safety precautions.
Finally, at the high school level students will explain how current is
controlled in simple, series and parallel circuits. They also will
consider the interaction of wires and magnets to produce electric
currents.
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