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Teaching Fractions: New methods, new resourcesMichael Meagher June 2002 |
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The
teaching of fractions continues to hold the attention of
mathematics teachers and education researchers
worldwide. In what order should various representations
be introduced? Should multiple representations be
introduced early, or one representation pursued in depth
once? Does it matter if fractions are introduced as
counting or as measurement? What is the relative
importance of procedural, factual, and conceptual
knowledge in success with fractions? These and other
questions remain debated in the literature. Following
an overview of recent research on teaching and learning
fractions, suggestions are offered for practice, for
locating resources having direct application in the
classroom, and for further reading in the research
literature. Student
conceptions
The
domain of skill and knowledge referred to as
"fractions" or "rational numbers"
has been parsed in various ways by researchers in recent
years. Tzur (1999) sees children's initial
reorganization of fraction conceptions as falling into
three strands: (a) equidivision of wholes into parts,
(b) recursive partitioning of parts (splitting), and (c)
reconstruction of the unit (i. e. the whole).
Recognizing this division, he suggests that teachers
consider one of these strands at a time in teaching
rational numbers. Taking
a psychological approach Moss and Case (1999) suggest
that for whole numbers children have two natural schema,
one for verbal counting and the other for global
quantity comparison. In the realm of rational numbers
they also see children as having two natural schema: one
global structure for proportional evaluation and one
numerical structure for splitting/doubling. They
propose, then, as a plan for learning that teachers need
to refine and extend naturally occurring processes. Hunting's
(1999) study of five-year-old children focused on early
conceptions of fractional quantities. He suggested that
there is considerable evidence to support the idea of
"one half" as being well established in
children's mathematical schema at an early age. He
argues that this and other knowledge about subdivisions
of quantities forming what he calls "prefraction
knowledge" (p.80) can be drawn upon to help
students develop more formal notions of fractions from a
very early age. Similarly, based on her successful
experience of teaching addition and subtraction of
fractions and looking for a way to teach multiplication
of fractions, Mack (1998) stresses the importance of
drawing on students’ informal knowledge. She used
equal sharing situations in which parts of a part can be
used to develop a basis for understanding multiplication
of fractions; e.g. sharing half a pizza equally among
three children results in each child getting one half of
one third. Mack noted that students did not think of
taking a part of part in terms of multiplication but
that their strong experience with the concept could be
developed later. Taking
an information-processing approach (Hecht, 1998) divides
knowledge about rational numbers into three strands:
procedural knowledge, factual knowledge, and conceptual
knowledge. Hecht's study isolated the contribution of
these types of knowledge to children's competencies in
working with fractions. He made two major conclusions:
(a) conceptual knowledge and procedural knowledge
uniquely explained variability in fraction computation
solving and fraction word problem set up accuracy, and
(b) conceptual knowledge uniquely explained individual
differences in fraction estimation skills. The latter
conclusion supports the general consensus in current
research that a holistic approach to teaching of
fractions is necessary with recommendations for a move
away from attainment of individual tasks and towards a
development of global cognitive skills. Mistakes
teachers make
Based
on previous research Moss and Case (1999) identified
four major problems with current teaching methods in the
area of fractions. The first is a syntactic rather than
a semantic emphasis, which is to say that researchers
have identified that teachers often emphasize technical
procedures in doing fraction arithmetic at the expense
of developing a strong sense in children of the meaning
of rational numbers. The second problem identified is
that teachers often take an adult-centered rather than a
child-centered approach, emphasizing fully formed adult
conceptions of rational numbers. As a result teachers
often do not take advantage of students "prefractional
knowledge" and their informal knowledge about
fractions thus denying children a spontaneous
"in" to their formal study of fractions. A
third issue is the problem of teachers using
representations in which rational and whole numbers are
easily confused e.g. students count the number of shaded
parts of a figure and the total number of parts so that
each part is regarded as an independent entity or amount
(Kieran cited in Moss & Case (1999). Finally,
researchers have identified considerable problems in use
of notation that can act as a hindrance to student
development. These problems center around teachers’
perceptions that the notation used for rational numbers
is transparent while this has been shown not to be the
case, especially with regard to decimal fractions (Hiebert,
cited in Moss & Case (1999)). Tirosh (2000)
conducted a study on teacher knowledge in teaching of
fractions and concluded that teachers needed to pay
considerably more to analysis of student errors. New
teaching approaches
Moss
and Case identified three different proposals on
approaches to teaching of fractions that address the
above mentioned problems in various ways and then
propose a new curricular approach which they tested
themselves in a study involving fifth and sixth grade
students. The first of the older studies conducted by
Hiebert and Warne (as cited in Moss & Case (1999))
was judged to have addressed primarily the syntactic and
notational problems mentioned above and placed a great
deal of emphasis on the use of base 10 blocks. In the
second study Kieran (as cited in Moss & Case (1999))
was seen to address the syntactic and representational
issues and, among other innovations, used paper folding
to represent fractions in preference to pie charts. The
third of the studies, conducted by Streefland (as cited
in Moss & Case (1999)) attempted to address all four
concerns and was based on using real-life situations to
develop children's understanding of rational numbers. Moss
and Case's (1999) own approach was designed to address
all four of the identified problems and was
characterized by several qualities distinguishing it
from previous approaches. They started with beakers
filled with various levels of water and asked students
to label beakers from 1 to 100 based on their fullness
or emptiness. They emphasized two main strategies:
halving (100 -> 50 -> 25) and composition (50 + 25
=75) in determining appropriate levels. Refining this
approach they developed the notion of two place decimals
with five full beakers and one three-quarter full beaker
making 5.75 beakers. Four place decimals were then
introduced with 5.2525 (initially, spontaneously denoted
as 5.25.25 by the students) characterised as lying one
quarter of the way between 5.25 and 5.26. Students
eventually went on to work on exercises where fractions,
decimals and percentages were used interchangeably. Moss
and Case found that this approach produced deeper, more
proportionally based, understanding of rational numbers.
They see their approach as having four distinctive
advantages over traditional approaches: (a) a greater
emphasis on meaning (semantics) over procedures, (b) a
greater emphasis on the proportional nature of fractions
highlighting differences between the integers and the
rational numbers, (c) a greater emphasis on children's
natural ways of solving problems, and (d) use of
alternative forms of visual representation as a mediator
between proportional quantities and numerical
representations (i. e. an alternative to the use of pie
charts). References
Hecht,
Steven Alan. (1998). Toward an Information-Processing
Account of Individual Differences in Fraction Skills. Journal
of Educational Psychology. 90 (3)
545-59. Hunting,
Robert P. (1999). Rational-number learning in the early
years: what is possible?. In J. V. Copley. (Ed.), Mathematics
in the early years, (pp 80-87). Reston, VA: NCTM. Mack,
Nancy K. (1998). Building a Foundation for Understanding
the Multiplication of Fractions. Teaching Children
Mathematics. 5 (1) 34-38. Moss,
Joan & Case, Robbie. (1999). Developing Children's
Understanding of the Rational Numbers: A New Model and
an Experimental Curriculum. Journal for Research in
Mathematics Education. 30 (2) 122-47 Tirosh,
Dina. (2000). Enhancing Prospective Teachers' Knowledge
of Children's Conceptions: The Case of Division of
Fractions. Journal for Research in Mathematics
Education. 31 (1) 5-25. Tzur,
Ron. (1999). An Integrated Study of Children's
Construction of Improper Fractions and the Teacher's
Role in Promoting That Learning. Journal for Research
in Mathematics Education. 30 (4) 390-416. World
Wide Web Resources
Visual
Fractions
This
World Wide Web (WWW) site is designed to help users
visualize fractions and the operations that can be
performed on them. There are instructions and problems
to work through for the operations of addition,
subtraction, multiplication, and division, first using
fractions and then working with mixed numbers. Number
lines are used to picture the addition and subtraction
problems while an area grid model is used to illustrate
multiplication and division problems. http://www.visualfractions.com/ The
Sounds of Fractions: Math in Music
“Overview
- You've probably heard that math and music are related,
but you may not have ever heard how or why. Objective:
- Compare math and music to see how mathematical
concepts of ratio, proportion, common denominator,
frequency, and amplitude connect with musical elements
such as time signature, pitch, tone, and rhythm” http://www.highwired.com/Classroom/Project/0,2069,23713-68258,00.html No
Matter What Shape Your Fractions are In
“Description:These
activities are designed to cause students to think; they
are not algorithmic. They do not say, To add fractions,
do step one, step two, step three. Students will explore
geometric models of fractions and discover relations
among them. Appropriate
Grades: 3rd - 6th, maybe. But precocious kindergarteners
could do some of it, and middle schoolers needing
another look at fractions could appreciate it as well.
"Drawing Fun Fractions" would be good for most
middle school students.” http://math.rice.edu/~lanius/Patterns/ Flashcards
This
web site was developed to help students improve their
math skills interactively. Students can test their
mathematics skills with Flashcards which give students
practice problems to try and then gives them feedback on
their answers. Students can also create and print your
own set of flashcards online. http://www.aplusmath.com/Flashcards/fractions-mult.html Fractions
in the ERIC Database
There are over 1,000 records in the ERIC database pertaining to fractions. The best way to locate those records is to search the database using one or both of the following ERIC Descriptors: fractions or decimal fractions. You can narrow your search by combining these two Descriptors with others, such as teaching methods, educational strategies, instructional materials, research, literature reviews, mathematics instruction, mathematics materials, mathematics curriculum, or mathematics skills. You can further narrow your search by using education level Descriptors, such as elementary education, middle schools, intermediate grades, or junior high schools, or individual grade levels. You can search the database on the Web at http://ericir.syr.edu/Eric/adv_search.shtml. |
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