Name: Jackson Chen
Killarney Secondary, Mathematics 9
Topic: Powers and Exponents
Preplanning questions:
(1)
Why do we teach this unit to
secondary school students?
Exponents expand on students’ existing
knowledge on multiplication and present a simpler way to denote repeated
multiplications of the same number without writing the operations out. This
way, it is possible to express extremely large or small numbers using only
single-digit integers.
The concept of powers and exponents
appears in a variety of subject areas that students will encounter later,
such as physics, chemistry and economics. It also has many real-world
applications like calculating growth rates (population, bank account, etc.)
and in units of measurement. For example, when students grow up, they will
need to know what the square feet of a house means, or why the storage of
their electronic devices are labelled in gigabytes.
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(2)
A mathematics project connected to this unit:
For
this unit, students will be asked to work in pairs and complete an art
project, where they must build a model for a house/building/architecture whose
surface area (walls + roof) formula must include the following:
·
A base power of 2
·
A base power of 3
·
A base power of 5
·
A zero exponent
·
A negative exponent
·
Two different positive exponents
The
dimensions of the model should be limited to centimeters (and approximated to
the nearest millimeter when measured with ruler). Each group should also
provide an elevation drawing/plan of their work with labelled dimensions. The
final model should be visually proportional to the drawings.
Students
are encouraged to replicate a renowned architecture, or to design and name an
original and make them as aesthetically pleasant as possible (any decorations
will NOT count towards the surface area calculations).
Students
will also be presented a series of sample pictures/models that they can use
as inspirations. This will be an opportunity to incorporate any indigenous
aspects into teaching. One idea is to use the Waap Galts’ap Community House
in Terrace, BC as a sample (pictured) and explaining a brief history of the
first nations and how the surface area of this specific building can be
calculated.
In the
end, one lesson will be dedicated to a math fair style activity in which
students will see every project and try to write the formula and calculate
the surface areas of each group’s creation (a worksheet will placed beside
each object for ‘visitors’ to write down their answers). In the end, the
projects, drawings and worksheets will be collected for grading and
assessment.
The
projects will be evaluated on the students’ understanding of exponents (base,
power, negative and zero exponents) through their applications in surface
area formulas. The checklist of requirements is helpful to guide students
toward their project, as well as the evaluation process. By asking students
to observe and explore each other’s projects, the teacher can also get an
indication of whether students have developed a deep understanding of the
topic.
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(3) Assessment
and Evaluation:
The unit is divided into four sections:
basic use of exponents to describe numbers, exponent laws, order of
operations and problem solving. The formal assessment
involves a quiz at the end of each section, followed by a unit test. The
questions will follow closely to classroom activities and homework
assignments. Students will also be assessed informally through classroom
activities and the group project participation, so that their level of
understanding can be gauged and used as a benchmark for formal evaluations.
Students are constantly encouraged to ask questions to clear any
uncertainties about the topic.
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Elements of unit plan:
a)
Lesson
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Topic
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1
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Using
exponents to describe numbers (power, base, exponent, exponential form)
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2
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Powers
with negative exponents
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3
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Exponent
laws (multiplication, division, raising a power, raising a product or
quotient to exponent, exponent of zero)
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4
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Review/assessment
of exponents (part 1)
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5
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Order
of operations (introduce applications and assign project)
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6
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Using
exponents to solve problems (geometry)
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7
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Using
exponents to solve problems (growth rates)
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8
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Review/assessment
of exponents (part 2)
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9
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Project
planning/homework review
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10
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Project
presentation day
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11
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Final
chapter assessment
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LESSON PLAN #1 – USING
EXPONENTS TO DESCRIBE NUMBERS
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Lesson Overview
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This lesson is designed
to introduce to students how to use exponents to represent repeated
multiplications, and the new vocabularies that are attached with learning exponents.
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Duration
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60 minutes
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Materials Required
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Paper, pen
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Introduction
(10 minutes)
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·
Begin with an activity:
ask students to fold a piece of paper (length and width cut roughly to same
length) in half, then repeat the same step three more times. Once opened up,
notice how many ‘squares’ have been formed
·
Explain the concept of
doubling something over and over again can be written in another way other
than 2x2x2x2…
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Presentation
(15 minutes)
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· Introduce the terms:
power, base, exponents
·
Detail the ways in which
the exponent form can be read (i.e. two to the fourth)
·
Briefly discuss the
history of exponents (Euclid was first to use the term “power”)
·
Go through two examples
where the base and power are not 2
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Activity
(10 minutes)
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·
Work through an exponents
table that has exponents in one column and numerical values in the other
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Presentation
(5 minutes)
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·
Show that the volume of a
cube can be expressed in exponents
·
List out other formulas
that have exponents (i.e. area of square)
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Activity
(20 minutes)
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·
Using the paper they have
folded, students will work in groups of 4 to figure out how many ‘squares’
there are on the four pieces of paper using only exponents
·
Can you build a cube
using ALL the squares (if you cut them out)?
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LESSON PLAN #2 –EXPONENT LAWS
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Lesson Overview
|
The objective of this
lesson is to familiarize students with operations on powers
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Duration
|
60 minutes
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Materials Required
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Paper, pen
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Activity
(10 minutes)
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·
Pose the following
problem: if we extend the length of a 2x1 rectangle by one unit repeatedly,
what happens to the area?
·
Express the pattern in a
provided table
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Presentation
(15 minutes)
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·
Introduce the multiplication
and division of powers
·
Demonstrate two methods
to obtain the answers, one of which follows the law of exponents
·
Similarly, introduce what
happens when you raise a power to an exponent
·
Briefly talk about Moore’s
Law and how it is relevant today
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Review
(15 minutes)
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·
Assign problems for students
to review the exponent laws
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Presentation
(10 minutes)
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·
Ask students what happens
when the exponent is zero? Explain the reason using a table
·
What about when the base
is zero?
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Questions
(10 minutes)
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·
Can one side of a shape
have an exponent of zero? What about negative?
·
Do negative exponents imply
that the number is smaller than the base? Examples?
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LESSON PLAN #3 – USING
EXPONENTS TO SOLVE PROBLEMS
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Lesson Overview
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The aim of the lesson is to introduce problems
in geometry and other applications that require exponents to solve
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Duration
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60 minutes
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Materials Required
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Paper, pen
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Introduction
(10 minutes)
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·
Review the lesson about
volumes and areas, incorporating exponents and operations
·
Use a more complex object
(such as a soda cans or silo) to devise a formula
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Presentation
(10 minutes)
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·
Explain methods to find
the volume and surface areas of different objects
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Activity
(20 minutes)
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·
Allow time for students
to work on their projects, based on ideas that were just covered in class
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Presentation
(10 minutes)
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·
Introduce problems with
growth rates and how exponents can be applied
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Demonstrate a population
growth rate problem
·
Discuss with students how
population growth could be an issue given the way we use resources today
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Activity
(10 minutes)
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·
Find the population of
Canada in 50 years given the current growth rate
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What implications are
there?
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