Wednesday, October 13, 2010

quadratic factoring with algebra tiles

Topic:  Factoring Quadratic Trinomials Using Algebra Tiles 
Group:  Howard, Maria, Raman                  
Intended Students:    Grade 10  Fundamentals and Pre-calculus

I.    BRIDGE  -   (1 minute)
Give everyone a small  sheet of paper.   In 5 seconds, write as many factors of 60.

II.   LEARNING OBJECTIVES:   Using the algebra tiles, students will be able to:
       2.1   factor quadratic trinomials, including perfect square trinomials
       2.2   relate the dimensions of a rectangular area with finding the factors of a trinomial
       2.3   experience three modes of factoring trinomials:  algebraic method, concrete algebra
               tiles, and virtual  manipulatives

III.  TEACHING OBJECTIVES
        3.1   maximum engagement of all students
        3.2   individual  hands-on-learning using math manipulatives  (algebra tiles)
        3.3   demonstration of using  virtual manipulatives in factoring trinomials

IV.   PRE-TEST  (Each student will be given a worksheet sheet       (2 minutes)
        4.1   Factor the trinomial:    x2  +  5x  +  6.    Write answer in worksheet.
             Show of hands who got the correct answer.  Ask a student to briefly explain her answer.

V.   PARTICIPATORY LEARNING   (9 minutes)
        5.1    State the learning objectives.  Tie-up bridge and pre-test to objectives.
        5.2     What are the factors of 6? (3 and 2)  How can we illustrate this geometrically? (Draw a  3 by 2 rectangle, divided into 6 squares).   How are factors related to dimensions (of length and width), and product related to area?  (Finding the factors of a number is the same as finding the dimensions of a rectangle whose area is the number)  Will this geometric representation work for finding factors of a trinomial?
        5.3   Distribute/introduce the algebra tiles, as a geometric method of finding factors of trinomials.  Each student will be given a complete set of tiles, with a transparent tile board.    Walk the students through the 3 different tile sizes representing   x2  (green),   x  (white)   and  1  (red)    Explain that x is a variable that can represent any positive number.
        5.4    Assemble 2-green x2,   5-white x  tiles and 2-red 1-tiles.  If all the 9 pieces represent the area of a rectangle, what algebraic expression represents  this area?  (2x2  +  5x  +  2)  How can we get the dimensions of this rectangle?  In your worksheet, complete the equation #2:    2x2  +  5x  +  2  =   (       )  (      )
        5.5    Empty your tile board.  For our  second rectangle, assemble 1- green x2,  6-white x and 9-red 1-tiles into a rectangle.  What expression represents the area of this rectangle?  (x2  +  6x  +  9).  What are the factors?    ( x + 3)  and (x  +  3).  What do you notice with our rectangle?  (It is a square).  Introduce the perfect square trinomial (PST).  In your worksheet, complete equation #3:  x2  +  6x  +  9  =  (    )  (      )  =  (        )2
       5.6    Virtual Manipulatives:    Reiterate that finding the linear factors of a quadratic trinomial is very much related to finding the dimensions of a rectangle that contain the trinomial.  The internet is full of virtual manipulatives that offer fun, creative, and interactive ways of factoring trinomial, which may  appeal to today’s technology-savvy students.  Factor x2  +  7x  +  12. =   (      )(        ).

VI.   Posttest:     Using your algebra tiles, find values of k, where x +kx  +  6 factors into 2 binomials. (k=5,7).  Write answer in #5 of your worksheet.

VII.   SUMMARY/CLOSURE:    Ask students what they have learned today, which should touch the following points:    (3 minutes)
1.    That to the concept of factoring is very much related to finding the dimensions of a rectangle
        of a given area.
2.    That a quadratic trinomial factors only if one can arrange it into a rectangle.
3.    That we know that a trinomial is a perfect square if the tiles neatly arranges into a square,
        with 2 equal dimensions.
4.    Ask students to complete # 6 & 7 of their worksheet.  Collect worksheets.


Student  Worksheet :
Name:  __________________                                      Topic:  Factoring Quadratic Trinomials
1.    Factor:    x2  +  5x  +  6 
2.    2x2  +  5x  +  2   =    (                ) (                  )
3.    x2  +  6x  +  9    =   (                 ) (                  )  =  (                )2
4.    x2 +  7x  +  12.   =   (                  ) (                  )
5.    x2  +  kx  +  6   =   (                   )(                    )  or (                   )(                   ) 
6.    One thing I learned today is _____________________________________.
7.    Algebra tiles do/do not help in understanding factoring trinomials because_______________________________________________________.


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