Educational researchers formulated the basic questions
about ability grouping decades ago. Does anyone benefit from grouping?
Who benefits most? Is anyone harmed? How? How much? Why? But after
more than a half-century of analysis and interpretation, reviewers
of the research findings have still not reached agreement on the
answers. For every research reviewer who has concluded that grouping
is helpful, there is another who
has concluded that it is harmful.
Today, however, researchers are using statistical
methods to organize and interpret the research literature on grouping,
and they are more hopeful than ever before of coming to a consensus
on what the research says. Glass (1976) coined the term meta-analysis
for this statistical approach to literature reviews. Researchers
who carry out a meta-analysis locate studies of an issue by clearly
specified procedures, code outcomes and features of the studies
on quantitative scales, and use statistical techniques to relate
characteristics of studies to outcomes. The approach yields reliable
and precise summaries of large bodies of research.
Two major sets of meta-analyses on research findings
on grouping have been completed, one set at the University of
Michigan (e.g., J. Kulik & Kultk, 1991) and the other at Johns
Hopkins University (Slavin, 1987.1990). The two sets of meta-analyses
together examine findings from five kinds of grouping programs:
- XYZ classes. School personnel
assign students by aptitude to classes (e.g., high, middle,
and low classes), and the classes are instructed in separate
rooms either for a full day or for a single subject. Highly
similar or identical curricular materials are usually used In
all classes at the same grade level.
- Cross-grade grouping. Children
from several grades who are at the same level of achievement
in a subject are formed into groups, and the groups are then
taught the subject in separate classrooms without regard to
the children's regular grade placement. Different curricular
materials are thus used with same-age students who are at different
aptitude levels.
- Within-class grouping. A teacher
forms ability groups within a single classroom and provides
each group with instruction appropriate to its level of aptitude.
The teacher usually uses different rates of instruction and
different instructional materials for the within-class groups.
- Accelerated classes. Students
who are unusually high in academic aptitude receive instruction
that allows them to proceed more rapidly through their schooling
or to finish schooling at an earlier age than other students.
The curriculum is clearly adapted to the higher aptitude level
of students in these programs.
- Enriched classes. Students who
are unusually high in aptitude receive richer, more varied educational
experiences than would be available to them in regular classes.
Like accelerated programs, these enriched classes provide a
curriculum that is specially tailored to students of higher
aptitude levels.
Findings from the Michigan and Johns Hopkins meta-analysis
agree quite well, but overall conclusions of the two research
teams differ. The Michigan team found no clear effects of grouping
in some programs, moderate positive benefits in others and huge
positive benefits in still others. Hopkins researchers found moderate
positive benefits from some grouping programs and no negative
or positive effects from others. The difference in conclusion
seems to stem from differences in the scope of the Michigan and
Hopkins analyses. The Michigan analysts concluded that the strongest
benefits from grouping were found in programs in which there was
a great deal of adjustment of curriculum for highly talented learners.
The Hopkins meta-analysts did not find any strong positive effects
of grouping, but they also did not examine grouping programs designed
for highly talented students.
A careful re-analysis of findings from all the
studies included in the two sets of meta-analyses confirmed that
higher aptitude students usually benefit academically from ability
grouping. The academic benefits are positive but usually small
when the grouping is done as a part of a broader program for students
of all abilities. For example, XYZ grouping, in which little or
no effort is made to adjust curriculum to the ability level of
the classes, raise the test scores of higher ability students
by about 0.1 standard deviations, or by about 1 month on grade-equivalent
scale. Within-class and cross-grade programs, which entail moderate
amounts of curricular adjustment, boost test scores of higher
aptitude students by about 0.2 to 0.3 standard deviations, or
by 2 to 3 months on a grade-equivalent scale.
Benefits are larger in special classes for higher
aptitude learners. Gains on standardized tests are especially
large when the programs entail acceleration of instruction. Classes
in which talented children cover four grades in three years, for
example, usually boost achievement levels a good deal. Test scores
of children accelerated in this fashion are about one year higher
on a glade-equivalent scale than they would be if the children
were not accelerated. Enriched classes, in which students have
a varied educational experience, raise test scores by more moderate
amounts. The average gain from such classes is 4 months on the
grade-equivalent scales of typical standardized tests. Although
smaller than the gains from accelerated classes, gains of this
size are still impressive because in many enriched classes students
spend as much as half their time on cultural material (e.g., foreign
languages, music, art) that is not directly tested on standard
achievement tests.
The re-analysis also showed that grouping has
less influence on the school work of middle and lower aptitude
learners. XYZ classes, for example, have virtually no effect on
the achievement of such students. Test scores of middle and lower
aptitude students taught in XYZ classes are indistinguishable
from test scores of similar students in mixed classes. Cross-grade
and within-class programs, however, usually raise test scores
of middle and lower aptitude pupils by between 0.2 and 0.3 standard
deviations. The adjustment of curriculum to pupil ability in within-class
and cross-grade programs may be the key.
Evidence was less clear on the noncognitive outcomes
of grouping programs. One conclusion is that grouping programs
usually have only small effects on student self-esteem. The programs
certainly do not lead talented students lo become self-satisfied
and smug, nor do they cause a precipitous drop in the self-esteem
of lower aptitude students. If anything, XYZ grouping may have
effects in the opposite direction. XYZ programs may cause quick
learners to lose a little of their self-assurance, and they may
cause slower learners to gain some badly needed self-confidence.
The available literature also suggests that grouping programs
may have some program specific effects in noncognitive areas.
For example, a few programs of accelerated instruction clearly
have an effect on the vocational plans of youngsters; other programs
of acceleration have no consistent effect.
These conclusions are obviously different from
the well-known conclusions reached by Oakes (1985) in her book
Keeping Track. According to Oakes,
students in the top tracks gain nothing from grouping and other
students suffer clear and consistent disadvantages, including
loss of academic ground, self-esteem, and ambition. Oakes also
believes that tracking is unfair to students because it denies
them their right to a common curriculum. She therefore calls for
the de-tracking of American schools. De-tracked schools would
provide the same curriculum for all, and they would not offer
special educational opportunities to any on the basis of ability,
achievement, or interests.
Oakes's conclusions, however, are based on her
own selective and idiosyncratic review of older summaries of the
literature and on her uncontrolled classroom observations. Objective
analysis of findings from controlled studies provides little support
for her speculations. Whereas Oakes believes that grouping programs
are unnecessary, ineffective, and unfair, the opposite appears
to be true. American education would be harmed by the wholesale
elimination of programs that group learners for instruction by
ability.
The harm would be relatively small from the simple
elimination of XYZ programs in which high, middle, and low classes
cover the same basic curriculum. If schools replaced all their
XYZ classes with mixed ones, the achievement level of higher aptitude
students would fall slightly, but the achievement level of other
students would remain about the same. If schools eliminated grouping
programs in which all groups follow curricula adjusted to their
ability, the damage would be greater, and It would be felt more
broadly. Bright, average, and slow students would suffer academically
from elimination of such programs. The damage would be greatest,
however, if schools, in the name of de-tracking, eliminated enriched
and accelerated classes for their brightest learners. The achievement
level of such students falls dramatically when they are required
to do routine work at a routine pace. No one can be certain that
there would be a way to repair the harm that would be done if
schools eliminated all programs of enrichment and acceleration.
References
Glass, G.V. (1976). Primary, secondary, and
meta-analysis of research. Educational Researcher,
5, 3-8.
Kulik, J.A. & Kulik C-L.C. (1991). Ability
grouping and gifted students. In N. Colangelo and G.A. Davis (Eds.)
Handbook of gifted education (pp.
178-196). Boston, MA: Allyn & Bacon.
Oakes, J. (1985) Keeping
track: How schools structure inequality. New Haven, CT:
Yale University Press.
Slavin, R.E. (1987). Ability grouping and
student achievement in elementary schools: A best-evidence synthesis.
Review of Educational Research, 57,
293-336.
Slavin, R.E. (1990). Achievement effects
of ability grouping in secondary schools. A best-evidence synthesis.
Review of Educational Research, 60,
471-499.
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