“algebra” in elementary schools: it’s not about x’s and...
TRANSCRIPT
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“Algebra” in Elementary Schools:It’s Not About x’s and y’s
2007 NCTM Conference
Atlanta, Georgia
Tad Watanabe
Kennesaw State [email protected]
http://science.kennesaw.edu/~twatanab
• What should elementary school algebra looklike?
• What are the fundamental ideas of algebrathat are appropriate for investigation byelementary school students?
• What ideas related to algebra are discussedin the Japanese elementary schoolcurriculum?
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Materials Studied
Content Strands in the JapaneseCourse of Study (COS)
QuantitativeRelations
QuantitativeRelations
Numbers & Shiki
Geometric Figures
Numbers & Calculations
Quantities & Measurements
Geometric Figures
Gr. 7 - 9Gr. 3 - 6Gr. 1 - 2
Lower SecondaryElementary
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(shiki)
• 3 + 5 = 8
• 8 + 4
• 11 > 8 + 5
• 3x + 4 = 16
• 2x + 3y
• etc.
Content Strands in the JapaneseCourse of Study (COS)
QuantitativeRelations
QuantitativeRelations
Numbers & Shiki
Geometric Figures
Numbers & Calculations
Quantities & Measurements
Geometric Figures
Gr. 7 - 9Gr. 3 - 6Gr. 1 - 2
Lower SecondaryElementary
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Quantitative Relations
The objectives and contents of thisdomain cover a wide range, but can bedivided into three categories: idea offunction, writing and interpretingmathematical expressions, andstatistical manipulation.
(Teaching Guide, p. 36)
Ideas of Functions
• How a product changes when the multiplierincreases or decreases by 1
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• Comparing and ordering numbers
• To view a number as a product of other numbers
• How a product increases when the multiplierincreases by 1
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• One-to-one correspondence
• To view a number as the sum or difference ofother numbers
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TopicsGrade
5
Ideas of Functions (cont.)
• Ratio and the value of ratio
• Proportion and its graph
• Inverse proportion
• Proportional relationships
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• Examination of quantitative relationshipsrepresented by formulas such as A x B = C
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• Dependency relation of two numbers and itsgraph
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TopicsGrade
Grade 1: Composition &Decomposition of Numbers
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Teachers’ ManualOne of the main objectives of this unit is to helpstudents see a number from multiple perspectives.This is a foundation for functional (algebraic)thinking because, in order to see a number inrelationship to others, we must pay attention toany dependency relationship or rule forcorrespondence. Thus, with decomposition of ten,once you pick “1”, then the other number, “9,” isdetermined. Furthermore, if the first numberincreases 1, 2, 3…, the other number will decrease9, 8, 7,…
Teachers’ ManualFirst graders cannot develop such aperspective automatically, and teachers maywant to order the (written) combinations ordisplay the blocks so that a pattern might benoticed visually.
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Grade 1: Addition
Grade 1: Subtraction
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Grade 2: Multiplication• What number do you need to add to 3x4 to
get the answer for 3x5. Find the answer for
3x6 by looking at the answer for 3x5.
Grade 2: MultiplicationIf you increase the multiplier of 4x3 by 1, how
much larger will the answer be? What if you
increase the multiplier of 4x4 by 1?
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Grade 2: Multiplication
• Constructing 6’s facts
“In the 6’s table, when themultiplier increases by 1,the product increases by6. So, …”
Grade 4: Covariation
• Fill a 1-liter measuring cup half-way.
• What happens if you tilt the measuring cup?– When the number on the left increases, the
number on the right ________.
– When the number on the right increases, thenumber on the left _______.
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Grade 5: Formulas
• Area of a parallelogram
• Area of a triangle
• Circumference of a circle
• Area of a circle
Grade 5: Examination offormulas
There is a parallelogram
with the height of 8 cm.
Let’s investigate what
happens to its area if its
base changes from 1 cm,
2 cm, …, 5 cm, without
changing the height.
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Grade 5: Examination offormulas
Let’s investigate how
the circumferences of
circles change when
their diameters
change.
Grade 6: Proportions
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Mathematical Expressions
• Writing and interpreting mathematical expressionsinvolving addition, subtraction, multiplication anddivision.
• Comparing numbers and quantities, and expressingtheir relationships.
• Writing and interpreting mathematical expressionsinvolving ( ).
• Using symbols such as and in mathematicalexpressions, and evaluating such expressions bysubstituting specific values.
Grade 1: Addition
Write shiki.
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Grade 1: Addition with a sum > 10
Takeshi picked 9 acorns. Miki picked 4acorns. How many acorns did they pickaltogether?
(1)Write an expression
(2)Let’s think about the method ofcalculation.
Grade 2: Multiplication
How many chocolatesare left in the box? Let’sfigure out different waysto find the answer.
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Treatment in the lower grades(Teaching Guide, p. 39)
Teaching about writing and interpretingmathematical expressions already started at thestage of learning addition in first grade… But,since concrete numbers are used in lower gradesand calculation immediately leads to one number,children rarely become aware of the fact that 3+4represents a concrete phenomenon. Therefore, itis important to teach children focus on themeaning of mathematical expressions instead ofpaying attention solely to getting results.
Grade 4: How many dots?Think about different ways to calculate the numberof dots.
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Grade 4: Writing as one shiki
• Makoto bought a hamburger for 130 yen anda cup of soup for 210 yen. He gave the clerk a500 yen coin. How much change will Makotoreceive?
Makoto: 130 + 210 = 340, 500 - 340 = 160.
Ritsuko: Can we represent this in one shiki?
Shiki with words
• [Amount You Paid] - [Cost] = [Change]
500 - (130 + 210) = 160
• [Area of Parallelogram] = [Base] x [Height]
• [Circumference] = [Diam.] x [Ratio ofCircum.]
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Shiki with words
Shiki with , , and Grade 2
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Shiki with , , and Grade 4
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Shiki with , , and Grade 5
A sheet of construction paper costs 30 yen.Write a shiki that can be used to calculate thetotal cost of construction paper, yen, whenyou buy sheets of construction paper.
If is 40, what number does represent?
Before x’s and y’s:• Represent relationships among quantities usingshiki with words.
• Use or to stand for unknown quantities towrite a shiki to represent relationships amongquantities.
• Substituting different values in in shiki, ordetermine the value of by reversing theoperations.
• When a relationship between two quantities andare represented in a shiki, the value of is
determined when we know the value of
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Representations to model problemsGrade 4
For the school sports festival, two fourthgrade teams are making 40 postersaltogether. Team B will make 8 moreposters than Team A. How many posterswill each team make?
Representations to model problemsGrade 5
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Representations to model problemsGrade 5
Concluding Thoughts
• Algebra in elementary schools goesmuch beyond the study of patterns.
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Algebra Standards (PSSM)
Instructional programs from prekindergarten
through grade 12 should enable all students
to—
– understand patterns, relations, and functions;
– represent and analyze mathematical situations
and structures using algebraic symbols;
– use mathematical models to represent and
understand quantitative relationships;
– analyze change in various contexts.
Principles and Standards forSchool Mathematics
When students notice that operations seem to have
particular properties, they are beginning to think
algebraically. For example, they realize that changing the
order in which two numbers are added does not change
the result or that adding zero to a number leaves that
number unchanged. Students' observations and
discussions of how quantities relate to one another lead
to initial experiences with function relationships, and
their representations of mathematical situations using
concrete objects, pictures, and symbols are the
beginnings of mathematical modeling.
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Concluding Thoughts
• Algebra in elementary schools goesmuch beyond the study of patterns.– Teachers need a deep understanding of
elementary school mathematics inrelationship to algebra.
– Curriculum materials need to articulatealgebraic thinking in elementary schoolmathematics more explicitly.
Grade 1Teachers Manual
•Algebra - Patterns:
children develop algebraic
thinking by finding all the
parts for a given total.
•After children discuss the
question on the page, ask:
how many ways can you
make a train for 4?”
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Grade 3: Multiplication
• Look at the facts with 3 as a
factor. What patterns do you
notice? (Problem for Ss)
• Students identify patterns,
which is important in
developing algebra sense.
Have students make a list of
multiplication facts with 3 as a
factor to see that they can
always add 3 to a fact to find
the next fact. (Manual)
Quantitative Relations
The contents of this domain include… itemswhich are useful in examining ormanipulating contents in other domains. …An important aim of this domain is tounderstand the contents of other domainsusing the ideas and methods discussed in thisdomain.
(Teaching Guide, p. 36)
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Concluding Thoughts
• Algebra in elementary schools goes muchbeyond the study of patterns.– Teachers need a deep understanding of
elementary school mathematics in relationshipto algebra.
– Curriculum materials need to articulatealgebraic thinking in elementary schoolmathematics more explicitly.
• Algebra in elementary schools is as much aprocess standard as a content standard.