- Algebra tiles
= Algebra Tiles =

**Algebra tiles**are known asmathematical manipulatives that allow students to better understand ways of algebraic thinking and the concepts ofalgebra . These tiles have proven to provide concrete models forelementary school ,middle school ,high school , and college-level introductoryalgebra students . They have also been used to prepareprison inmates for theirGeneral Educational Development (GED) tests. [*Kitts, N: "Using Homemade Algebra Tiles to Develop Algebra and Prealgebra Concepts", page 462. MATHEMATICS TEACHER, 2000.*]**Algebra tiles**allow both an algebraic and geometric approach to algebraic concepts. They givestudents another way to solve algebraic problems other than just abstract manipulation. [*Kitts, N: "Using Homemade Algebra Tiles to Develop Algebra and Prealgebra Concepts", page 463. MATHEMATICS TEACHER, 2000.*] TheNational Council of Teachers of Mathematics (NCTM ) recommends a decreased emphasis on the memorization of the rules ofalgebra and the symbol manipulation ofalgebra in their "Curriculum and Evaluation Standards for Mathematics". According to theNCTM 1989 standards " [r] elating models to one another builds a better understanding of each". [*Stein, M: Implementing Standards-Based Mathematics Instruction", page 105. Teachers College Press, 2000.*]**Physical Attributes**The

**algebra tiles**are made up of small squares, large squares, and rectangles. Thenumber one is represented by the small square, which is also known as the unit tile. The rectangle represents thevariable x and the large square represents x^{2}. Thelength of the side of the large square is equal to thelength of the rectangle, also known as the x tile. When visualizing these tiles it is important to remember that thearea of a square is s^{2}, which is the length of the sides squared. So if thelength of the sides of the large square is x then it is understandable that the large square represents x^{2}. The width of the x tile is the samelength as the side length of the unit tile. The reason that the**algebra tiles**are made this way will become clear through understanding their use infactoring and multiplyingpolynomials . [*Kitts, N: "Using Homemade Algebra Tiles to Develop Algebra and Prealgebra Concepts", page 462. MATHEMATICS TEACHER, 2000.*]Commercially made

**algebra tiles**are usually made from plastic and have one side of one color and the other side of another color. the difference in the color is supposed to denote one side that is positive and one side that is negative. Traditionally, one side is red to represent the negative and one side is green to represent the positive. [*Kitts, N: "Using Homemade Algebra Tiles to Develop Algebra and Prealgebra Concepts", page 462. MATHEMATICS TEACHER, 2000.*] Having the two colors on both sides allows for more numbers to be represented with a fewer number of tiles. It also makes it easier to change positives to negatives when performing a procedure such as multiplying a positive and a negative number. There are some tiles where the positive x and x^{2}tile will be the same color, but the positive unit tile is a different color. This representation is still alright to use, it is just important to have a least two colors to denote positive and negative. Some commercially made**algebra tiles**can be purchased for theoverhead projector . These are made out a plastic translucent material. [*http://www.eaieducation.com/525010.html Overhead Projector Algebra Tiles*]**Algebra tiles**can also be made athome instead of buying them commercially. Templates for the**algebra tiles**can be found online, [*http://www.teachervision.fen.com/algebra/printable/6192.html Algebra tile template*] , which can be printed and then cut out. [*[*] Once the shapes are cut out of the printer paper they can be used to cut out*http://www.teachervision.fen.com/algebra/printable/6192.html*]**algebra tiles**fromcard stock or Foamies, which arefoam -like materials, about 1/8-inch thick. [*http://www.regentsprep.org/regents/math/ALGEBRA/teachres/ttiles.htm Homemade Algebra Tiles*]**Algebra tiles**can also be made for theoverhead projector by cutting the shapes out of colored plastic report covers. [*Kitts, N: "Using Homemade Algebra Tiles to Develop Algebra and Prealgebra Concepts", page 463. MATHEMATICS TEACHER, 2000.*]**Uses****Adding Integers****Algebra tiles**can be used for addingintegers . [*Kitts, N: "Using Homemade Algebra Tiles to Develop Algebra and Prealgebra Concepts", page 463. MATHEMATICS TEACHER, 2000.*] To demonstrate this ability you can consider the problem $2+3=?$. In order to solve this problem using**algebra tiles**a person would group two of the positive unit tiles together and then group three of the positive unit tiles together to represent separately 2 and 3. In order to represent $2+3$ the person would then combine their two groups together. Once this step is complete the person can then count that together there are 5 unit tiles, so $2+3=5$. Since adding a number with the negative of that number gives you zero, for instance $-2+2=0$, adding a negative unit tile and a positive unit tile will also give youzero . When you add a positive tile and a negative tile it is known as the zero pair. In order to show that anyinteger plus its negative iszero a person can physically represent this concept through**algebra tiles**. Let us take the example used earlier where $-2+2=0$. A person would fist lay out two negative unit tiles and then two positive unit tiles, which would then be combined into two sets of zero pairs. These two sets of zero pairs would then be equal tozero . [*[*] Understanding zero pairs allows you to also add positive and negative integers that are not equal. An example of this would be $-7+4=?$, where you would group seven negative unit tiles together and then four positive unit tiles together and then combine them. Before you count the number of tiles that you now have you would have to create zero pairs and then remove them from you final answer. In this example you would have four zero pairs which would remove all of the positive unit tiles and you would be left with three negative unit tiles, so $-7+4=-3$.*http://www.phschool.com/professional_development/teaching_tools/pdf/using_algebra_tiles.pdf*]**Subtracting Integers****Algebra tiles**can also be used for subtractingintegers . A person can take a problem such as $6-3=?$ and begin with a group of six unit tiles and then take three away to leave you with three left over, so then $6-3=3$.**Algebra tiles**can also be used to solve problems like $-4-(-2)=?$. First you would start off with four negative unit tiles and then take away two negative unit tiles to leave you with two negative unit tiles. Therefore $-4-(-2)=-2$, which is also the same answer you would get if you had the problem $-4+2$. Being able to relate these two problems and why they get the same answer is important because it shows that $-(-2)=2$. Another way in which**algebra tiles**can be used forinteger subtraction can be seen through looking at problems where you subtract a positiveinteger from a smaller positiveinteger , like $5-8$. Here you would begin with five positive unit tiles and then you would add zero pairs to the five positive unit tiles until there were eight positive unit tiles in front of you. Adding the zero pairs will not change the value of the original five positive unit tiles you originally had. You would then remove the eight positive unit tiles and count the number of negative unit tiles left. This number of negative unit tiles would then be your answer, which would be -3. [*[*]*http://www.phschool.com/professional_development/teaching_tools/pdf/using_algebra_tiles.pdf*]**Multiplication of Integers**Multiplication ofintegers with**algebra tiles**is performed through forming a rectangle with the tiles. Thelength andwidth of your rectangle would be your twofactors and then the total number of tiles in the rectangle would be the answer to yourmultiplication problem. For instance in order to determine 3×4 you would take three positive unit tiles to represent three rows in the rectangle and then there would be four positive unit tiles to represent the columns in the rectangle. This would lead to having a rectangle with four columns of three positive unit tiles, which represents 3×4. Now you can count the number of unit tiles in the rectangle, which will equal 12.**Modeling and Simplifying Algebraic Expressions**Modeling algebraic expressions with

**algebra tiles**is very similar to modelingaddition andsubtraction of integers using**algebra tiles**. In an expression such as $5x-3$ you would group five positive x tiles together and then three negative unit tiles together to represent this algebraic expression. Along with modeling these expressions,**algebra tiles**can also be used to simplify algebraic expressions. For instance, if you have $4x+5-2x-3$ you can combine the positive and negative x tiles and unit tiles to form zero pairs to leave you with the expression $2x+2$. Since the tiles are laid out right in front of you it is easy to combine the like terms, or the terms that represent the same type of tile. [*[*]*http://www.phschool.com/professional_development/teaching_tools/pdf/using_algebra_tiles.pdf*]**Using the Distributive Property**The

distributive property is modeled through the**algebra tiles**by demonstrating that a(b+c)=(a×b)+(a×c). You would want to model what is being represented on both sides of the equation separately and determine that they are both equal to each other. If we want to show that $3(x+1)=3x+3$ then we would make three sets of one unit tile and one x tile and then combine them together to see if would have $3x+3$, which we would. [*[*]*http://www.regentsprep.org/rEGENTS/math/realnum/Tdistrib.htm*]**Solving Linear Equations**Manipulating

**algebra tiles**can help students solvelinear equations . In order to solve a problem like $x-6=2$ you would first place one x tile and six negative unit tiles in one group and then two positive unit tiles in another. You would then want to isolate the x tile by adding six positive unit tiles to each group, since whatever you do to one side has to be done to the other or they would not be equal anymore. This would create six zero pairs in the group with the x tile and then there would be eight positive unit tiles in the other group. this would mean that $x=8$. [*[*] You can also use the*http://www.phschool.com/professional_development/teaching_tools/pdf/using_algebra_tiles.pdf*]subtraction property of equality to solve yourlinear equation with**algebra tiles**. If you have the equation $x+7=10$, then you can add seven negative unit tiles to both sides and create zero pairs, which is the same as subtracting seven. Once the seven unit tiles are subtracted from both sides you find that your answer is $x=3$. [*Kitts, N: "Using Homemade Algebra Tiles to Develop Algebra and Prealgebra Concepts", page 464. MATHEMATICS TEACHER, 2000.*] There are programs online that allow students to create their ownlinear equations and manipulate the**algebra tiles**to solve the problem. [*http://my.hrw.com/math06_07/nsmedia/tools/Algebra_Tiles/Algebra_Tiles.html Solving Linear Equations Program*] This video from Teacher Tube also demonstrates how**algebra tiles**can be used to solve linear equations. [*http://www.teachertube.com/view_video.php?viewkey=7b93931b2e628c6e6244&page=&viewtype=&category= Teacher Tube Solving Equations*]**Multiplying polynomials**When using

**algebra tiles**to multiply amonomial by amonomial you first set up a rectangle where thelength of the rectangle is the onemonomial and then thewidth of the rectangle is the othermonomial , similar to when you multiplyintegers using**algebra tiles**. Once the sides of the rectangle are represented by the**algebra tiles**you would then try to figure out which**algebra tiles**would fill in the rectangle. For instance, if you had x×x the only**algebra tile**that would complete the rectangle would be x^{2}, which is the answer.Multiplication ofbinomials is similar tomultiplication ofmonomials when using the**algebra tiles**. Multiplication ofbinomials can also be thought of as creating a rectangle where thefactors are thelength andwidth . [*Stein, M: Implementing Standards-Based Mathematics Instruction", page 98. Teachers College Press, 2000.*] Like with themonomials , you set up the sides of the rectangle to be thefactors and then you fill in the rectangle with the**algebra tiles**. [*Stein, M: Implementing Standards-Based Mathematics Instruction", page 106. Teachers College Press, 2000.*] This method of using**algebra tiles**to multiplypolynomials is known as the area model [*Larson R: "Algebra 1", page 516. McDougal Littell, 1998.*] and it can also be applied to multiplyingmonomials andbinomials with each other. An example of multiplyingbinomials is (2x+1)×(x+2) and the first step you would take is set up two positive x tiles and one positive unit tile to represent thelength of a rectangle and then you would take one positive x tile and two positive unit tiles to represent thewidth . These two lines of tiles would create a space that looks like a rectangle which can be filled in with certain tiles. In the case of this example the rectangle would be composed of two positive x^{2}tiles, five positive x tiles, and two positive unit tiles. So the solution is 2x^{2}+5x+2.**Factoring**In order to factor using

**algebra tiles**you start out with a set of tiles that you combine into a rectangle, this may require the use of adding zero pairs in order to make the rectangular shape. An example would be where you are given one positive x^{2}tile, three positive x tiles, and two positive unit tiles. You form the rectangle by having the x^{2}tile in the upper right corner, then you have two x tiles on the right side of the x^{2}tile, one x tile underneath the x^{2}tile, and two unit tiles are in the bottom right corner. By placing the**algebra tiles**to the sides of this rectangle we can determine that we need one positive x tile and one positive unit tile for thelength and then one positive x tile and two positive unit tiles for thewidth . This means that the twofactors are $x+1$ and $x+2$. [*Kitts, N: "Using Homemade Algebra Tiles to Develop Algebra and Prealgebra Concepts", page 464. MATHEMATICS TEACHER, 2000.*] In a sense this is the reverse of the procedure for multiplyingpolynomials .**Completing the Square**The process of

completing the square can be accomplished using**algebra tiles**by placing your x^{2}tiles and x tiles into a square. You will not be able to completely create the square because there will be a smaller square missing from your larger square that you made from the tiles you were given, which will be filled in by the unit tiles. In order tocomplete the square you would determine how many unit tiles would be needed to fill in the missing square. In order tocomplete the square of x^{2}+6x you start off with one positive x^{2}tile and six positive x tiles. You place the x^{2}tile in the upper left corner and then you place three positive x tiles to the right of the x^{2}tile and three positive unit x tiles under the x^{2}tile. In order to fill in the square we need nine positive unit tiles. we have now created x^{2}+6x+9, which can be factored into $(x+3)(x+3)$. [*[*]*http://www.regentsprep.org/Regents/math/algtrig/ATE12/completesq.htm*]**Notes****References*** Kitt, Nancy A. and Annette Ricks Leitze. "Using Homemade Algebra Tiles to Develope Algebra and Prealgebra Concepts." "MATHEMATICS TEACHER" 2000. 462-520.

* Stein, Mary Kay et.al., "IMPLEMENTING STANDARDS-BASED MATHEMATICS INSTRUCTION". New York: Teachers College Press, 2000.

* Larson, Ronald E., "ALGEBRA 1". Illinois: McDougal Littell,1998.

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