| Standards for Grades 6–8 |
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In the
middle-grades mathematics classroom, young adolescents should regularly engage
in thoughtful activity tied to their emerging capabilities of finding and
imposing structure, conjecturing and verifying, thinking hypothetically,
comprehending cause and effect, and abstracting and generalizing. In these
grades, each student follows his or her own developmental timetable. Some
mature early, and others late. Some progress rapidly, others more slowly. Thus,
every middle-grades teacher faces the challenge of dealing with many aspects of
diversity. Yet students also display some commonalities. For example, young
adolescents are almost universally sensitive to the influence of their peers.
The differences in intellectual development and emotional maturity and the
sensitivity of individuals to peer-group perceptions make it especially
important for teachers to create classroom environments in which clearly
established norms support the learning of mathematics by everyone.
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An ambitious, focused
mathematics program for all students in the middle grades is
proposed in these Standards. Ambitious expectations are identified in algebra
and geometry that would stretch the middle-grades program beyond a
preoccupation with number. In recent years, the possibility and necessity of
students‘ gaining facility in algebraic thinking have been widely » recognized. Accordingly, these Standards propose
a significant amount of algebra for the middle grades. In addition, there is
a need for increased attention to geometry in these grades. Facility in
geometric thinking is essential to success in the later study of mathematics
and also in many situations that arise outside the mathematics classroom.
Moreover, geometry is typically the area in which U.S. students perform most
poorly on domestic and international assessments of mathematics proficiency.
Therefore, significantly more geometry is recommended in these Standards for
the middle grades than has been the norm. The recommendations are
ambitious—they call for students to learn many topics in algebra and geometry
and also in other content areas. To guard against fragmentation of the
curriculum, therefore, middle-grades mathematics curriculum and instruction
must also be focused and integrated.
Specific foci are identified
in several content areas. For example, in number and operations, these
Standards propose that students develop a deep understanding of
rational-number concepts, become proficient in rational-number computation
and estimation, and learn to think flexibly about relationships among
fractions, decimals, and percents. This facility with rational numbers should
be developed through experience with many problems involving a range of
topics, such as area, volume, relative frequency, and probability. In
algebra, the focus is on proficiency in recognizing and working effectively
with linear relationships and their corresponding representations in tables,
graphs, and equations; such proficiency includes competence in solving linear
equations. Students can develop the desired algebraic facility through
problems and contexts that involve linear and nonlinear relationships.
Appropriate problem contexts can be found in many areas of the curriculum,
such as using scatterplots and approximate lines of fit to give meaning to
the concept of slope or noting that the relationship between the side lengths
and the perimeters of similar figures is linear, whereas the relationship
between the side lengths and the areas of similar figures is nonlinear.
Curricular
focus and integration are also evident in the proposed emphasis on
proportionality as an integrative theme in the middle-grades mathematics
program. Facility with proportionality develops through work in many areas of
the curriculum, including ratio and proportion, percent, similarity, scaling,
linear equations, slope, relative-frequency histograms, and probability. The
understanding of proportionality should also emerge through problem solving
and reasoning, and it is important in connecting mathematical topics and in
connecting mathematics and other domains such as science and art.
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In the recommendations for
middle-grades mathematics outlined here, students will learn significant
amounts of algebra and geometry throughout grades 6, 7, and 8. Moreover, they
will see algebra and geometry as interconnected with each other and with
other content areas in the curriculum. They will have experience with both the
geometric representation of algebraic ideas, such as visual models of
algebraic identities, and the algebraic representation of geometric ideas,
such as equations for lines represented on coordinate grids. They will see
the value of interpreting both algebraically and geometrically such important
mathematical ideas as the slope of a line and the Pythagorean relationship.
They also will relate algebraic and geometric ideas to other topics—for
example, when they reason about percents using visual models or equations or
when they represent an approximate line of fit for a scatterplot both
geometrically and » algebraically. Students
can gain a deeper understanding of proportionality if it develops along with
foundational algebraic ideas such as linear relationships and geometric ideas
such as similarity.
Students’ understanding of
foundational algebraic and geometric ideas should be developed through
extended experience over all three years in the middle grades and across a
broad range of mathematics content, including statistics, number, and
measurement. How these ideas are packaged into courses and what names are
given to the resulting arrangement are far less important than ensuring that
students have opportunities to see and understand the connections among
related ideas. This approach is a challenging alternative to the practice of
offering a select group of middle-grades students a one-year course that
focuses narrowly on algebra or geometry. All middle-grades students will
benefit from a rich and integrated treatment of mathematics content.
Instruction that segregates the content of algebra or geometry from that of
other areas is educationally unwise and mathematically counterproductive.
Principles and Standards
for School Mathematics proposes
an ambitious and rich experience for middle-grades students that both
prepares them to use mathematics effectively to deal with quantitative
situations in their lives outside school and lays a solid foundation for
their study of mathematics in high school. Students are expected to learn
serious, substantive mathematics in classrooms in which the emphasis is on
thoughtful engagement and meaningful learning.
For those who make decisions
about the design and organization of middle-grades mathematics education, it
would be insufficient simply to announce new and more-ambitious goals like
those suggested here. School system leaders need to commit to and support
steady, long-term improvement and capacity building to accomplish such goals.
The capacity of schools and middle-grades teachers to provide the kind of
mathematics education envisioned needs to be built. Special attention must be
given to the preparation and ongoing professional support of teachers in the
middle grades. Teachers need to develop a sound knowledge of mathematical
ideas and excellent pedagogical practices and become aware of current
research on students‘ mathematics learning. Professional development is
especially important in the middle grades because so little attention has
been given in most states and provinces to the special preparation that may
be required for mathematics teachers at these grade levels. Many such
teachers hold elementary school generalist certification, which typically
involves little specific preparation in mathematics. Yet teachers in the
middle grades need to know much more mathematics than is required in most
elementary school teacher-certification programs. Some middle-grades
mathematics teachers hold secondary school mathematics-specialist
certification. But middle-grades teachers need to know much more about
adolescent development, pedagogical alternatives, and interdisciplinary
approaches to teaching than most secondary school teacher-certification
programs require. In order to accomplish the ambitious goals for the middle
grades that are presented here, special teacher-preparation programs must be
developed.
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摘自NCTM
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