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Northwest Two Year CollegeMathematics Conference 2006Using Visual Algebra Pieces to Model Algebraic Expressions and Solve Equations : 

Northwest Two Year CollegeMathematics Conference 2006Using Visual Algebra Pieces to Model Algebraic Expressions and Solve Equations Dr. Laurie BurtonMathematics DepartmentWestern Oregon Universitywww.wou.edu/~burtonl

Slide 2: 

These ideas useALGEBRA PIECES and the MATH IN THE MIND’S EYE curriculum developed at Portland State University (see handout for access)

What are ALGEBRA PIECES? : 

What are ALGEBRA PIECES? The first pieces are BLACK AND RED TILES which model integers: Black Square = 1 Red Square = -1

INTEGER OPERATIONS Addition : 

INTEGER OPERATIONS Addition 2 + 3 5 black total = 5

INTEGER OPERATIONS Addition : 

INTEGER OPERATIONS Addition -2 + -3 5 red total = -5

INTEGER OPERATIONS Addition : 

INTEGER OPERATIONS Addition -2 + 3 Black/Red pair: Net Value (NV) = 0Total NV = 1

INTEGER OPERATIONSSubtraction : 

INTEGER OPERATIONSSubtraction 2 - 3 Take Away?? Still Net Value: 2

INTEGER OPERATIONSSubtraction : 

INTEGER OPERATIONSSubtraction 2 - 3 Net Value: 2 2 - 3 = -1

You can see that all integer subtraction models may be solved by simply added B/R--Net Value 0 pairs until you have the correct amount of black or red tiles to subtract. : 

You can see that all integer subtraction models may be solved by simply added B/R--Net Value 0 pairs until you have the correct amount of black or red tiles to subtract.

This is excellent for understanding “subtracting a negative is equivalent to adding a positive.” : 

This is excellent for understanding “subtracting a negative is equivalent to adding a positive.”

INTEGER OPERATIONSMultiplication : 

INTEGER OPERATIONSMultiplication 2 x 3

INTEGER OPERATIONSMultiplication : 

INTEGER OPERATIONSMultiplication 2 x 3 Net Value = 62 x 3 = 6

INTEGER OPERATIONSMultiplication : 

INTEGER OPERATIONSMultiplication -2 x 3

INTEGER OPERATIONSMultiplication : 

INTEGER OPERATIONSMultiplication -2 x 3

INTEGER OPERATIONSMultiplication : 

INTEGER OPERATIONSMultiplication -2 x 3 Net Value = -6-2 x 3 = -6

Slide 16: 

-2 x -3 would result in TWO FLIPS (down the columns, across the rows) and an all black result to show -2 x -3 = 6These models can also show INTEGER DIVISION

BEYONDINTEGER OPERATIONS : 

BEYONDINTEGER OPERATIONS The next important phase is understanding sequences and patterns corresponding to a sequence of natural numbers.

TOOTHPICK PATTERNS : 

TOOTHPICK PATTERNS Students learn to abstract using simple patterns

TOOTHPICK PATTERNS : 

TOOTHPICK PATTERNS These “loop diagrams” help the students see the pattern here is 3n + 1: n = figure #

B / R ALGEBRA PIECES These pieces are used for sequences with Natural Number domain : 

B / R ALGEBRA PIECES These pieces are used for sequences with Natural Number domain Black N, N ≥ 0Edge NRed -N, -N < 0Edge -N Pieces rotate

ALGEBRA SQUARES : 

ALGEBRA SQUARES Black N2Red -N2Edge lengths match n stripsPieces rotate

Patterns with Algebra Pieces : 

Patterns with Algebra Pieces Students learn to see the abstract pattern in sequences such as these

Patterns with Algebra Pieces : 

Patterns with Algebra Pieces

Working with Algebra PiecesMultiplying(N + 3)(N - 2) : 

Working with Algebra PiecesMultiplying(N + 3)(N - 2) First you set up the edges

(N + 3)(N - 2) : 

(N + 3)(N - 2) Now you fill in according to the edge lengths FirstN x N = N2

(N + 3)(N - 2) : 

(N + 3)(N - 2) Inside3 x N = 3N OutsideN x -2 = -2N Last 3 x -2 = -6

(N + 3)(N - 2) : 

(N + 3)(N - 2) (N + 3)(N - 2) = N2 - 2N + 3N - 6 = N2 + N - 6

(N + 3)(N - 2) : 

(N + 3)(N - 2) This is an excellent method for students to use to understand algebraic partial products

Solving Equations N2 + N - 6 = 4N - 8? : 

Solving Equations N2 + N - 6 = 4N - 8? =

Solving Equations N2 + N - 6 = 4N - 8? : 

Solving Equations N2 + N - 6 = 4N - 8? = Subtract 4N from both sets: same as adding -4n

Solving Equations N2 + N - 6 = 4N - 8? : 

Solving Equations N2 + N - 6 = 4N - 8? = Subtract -8 from both sets

Solving Equations N2 + N - 6 = 4N - 8? : 

Solving Equations N2 + N - 6 = 4N - 8? = 0

Solving Equations N2 + N - 6 = 4N - 8? : 

Solving Equations N2 + N - 6 = 4N - 8? Students now try to factor by forming a rectangleNote the constant partial product will always be all black or all red = 0

Solving Equations N2 + N - 6 = 4N - 8? : 

Solving Equations N2 + N - 6 = 4N - 8? Thus, there must be 2 n strips by 1 n strip to create a 2 black square blockTake away all NV=0 Black/Red pairs = 0

Solving Equations N2 + N - 6 = 4N - 8? : 

Solving Equations N2 + N - 6 = 4N - 8? Thus, there must be 2 n strips by 1 n strip to create a 2 black square blockTake away all NV=0 Black/Red pairs = 0

Solving Equations N2 + N - 6 = 4N - 8? : 

Solving Equations N2 + N - 6 = 4N - 8? Form a rectangle that makes sense = 0

Solving Equations N2 + N - 6 = 4N - 8? : 

Solving Equations N2 + N - 6 = 4N - 8? Lay in edge pieces = 0

Solving Equations N2 + N - 6 = 4N - 8? : 

Solving Equations N2 + N - 6 = 4N - 8? Measure the edge sets = 0

Solving Equations N2 + N - 6 = 4N - 8? : 

Solving Equations N2 + N - 6 = 4N - 8? = 0 (N - 2)(N - 1) = 0 (N - 2) = 0, N = 2or (N - 1) = 0, N = 1

This last example; using natural number domain for the solutions, was clearly contrived. : 

This last example; using natural number domain for the solutions, was clearly contrived.

In fact, the curriculum extends to using neutral pieces (white) to represent x and -x allowing them to extend to integer domain and connect all of this work to graphing in the “usual” way. : 

In fact, the curriculum extends to using neutral pieces (white) to represent x and -x allowing them to extend to integer domain and connect all of this work to graphing in the “usual” way.

Materials : 

Materials Math in the Mind’s Eye Lesson Plans:Math Learning Center Burton: SabbaticalClassroom use modules

Packets for today:“Advanced Practice” : 

Packets for today:“Advanced Practice” Integer work stands alone Algebraic work; quality exploration provides solid foundation