SUPPORTS FOR LEARNING MULTI-DIGIT ADDITION AND
SUBTRACTION:
A STUDY OF TAIWANESE SECOND-GRADE LOW-MATH ACHIEVERS
Hsiu-fei Lee
Northwestern University
feifei@northwestern.edu
Taiwanese
second-graders were randomly chosen from 10 classes and 3 schools in Taiwan and
tested to compose a low-math-achiever (LMA) and high-math-achiever (HMA) group
(each n =37). All children were given an IQ test (Raven), a place-value
task, a written test of 2- and 3-digit addition and subtraction problems, and a
strategy interview of mental math problems. LMAs compared to HMAs had a less
mature place-value concept, used less sophisticated and slower procedures in
solving the addition but not the subtraction mental math problems, and
performed more poorly on the multi-digit addition but not subtraction problems.
The base-10-structured methods were favored by both groups when interviewed
about their strategies. A
"Linguistic and Visual Support" Model was proposed to explain the
unusual findings of subtraction easier than addition.
Rationale
In the past two decades, Asian
students have been the "winners" of various international studies in
math. These results sometimes lead to
the stereotype that all Asian students are math wizards who do not need to
struggle with math. However, little is
known about Asian low-math achievers.
The results of most current cross-national studies have failed to
explain why Asian low-math achievers do not do as well as their
normally-achieving peers, given the facts as most cross-cultural studies have
suggested (e.g., Stevenson & Stigler, 1992) that they all learn from a more
centralized math curriculum, use a more regular number-word system, and live in
a society where effort is more stressed and parental supports are more
available to a child's education. This
study initiates an examination of characteristics of Chinese low-math
achievers.
The theoretical framework was based
on a Vygotskiian socio-cultural perspective (1978, 1986) which postulates that
the formation of minds requires study of the sociocultural setting in which
activities take place. Thus, solution
strategies were examined to ascertain how well all children could use the
semiotic tools used in their culture in the context of math problem solving:
the regular Chinese number words that name the ten (e.g., 12 is said as
"ten two" and 32 is said as "three ten two") and the
10-structured methods of adding and subtracting taught in the classroom. “Make-a-ten” methods were predominantly used
in the class to solve addition problems.
These methods varied in which number made a 10: making the big number to
10 [e.g., 7+8 = (8+2)+5=15] or making the small number to 10 [e.g., 7+8
=5+(3+7)=15]. For subtraction problems,
the "make-a-ten" method was taught in class. This method splits the teen number into ten
and some (e.g., for 15-8: ten five (15) = ten and five, and the 8 is taken from
the 10 leaving 2 (many students just know 10-partners of all numbers), which is
combined with 5, the other part of 15, to make 7). Korean students (Fuson & Kwon, 1992a) use 2 related methods
that involve going up over ten or down over ten. Other methods that have been proposed by American researchers
(e.g., Fuson, 1988) such as doubles, or counting on were not emphasized in the
instruction either.
Methods
and Data Sources
Second-grade Chinese children from 3
schools in Taiwan chosen to span a range of typical schools (one in a city and
two in rural areas) were followed throughout their second-grade year. The subjects were randomly chosen from 10
classes randomly chosen from the three schools. Children from the top and bottom 10% of each class based on a
composite score of their math screening test given in the beginning of
second-grade and their first-grade math GPA made up the high-math-achiever (HMA:
n=37) and low-math-achiever (LMA: n=37) groups. A nonverbal IQ test (Raven) was used to choose children with IQ
in a normal range. Children included in
this study were also required to have no hearing or visual impairment and no
emotional problems. This information
was gathered from student's psychological reports and class teachers'
reports.
The math tasks included a
place-value task (the Kamii task), a written test of 2- and 3-digit addition
and subtraction problems (for details, see Fuson & Kwon, 1992b), and an
interview about their strategies of solving two single-digit mental math
problems (8+7, 14-6). The Kamii task
required children to show how many objects the number "1" means in
16. Students were given the 3-digit
problems before they had studied the topic in school. The goal was to examine whether they could transfer their
understanding and procedures in solving 2-digit to 3-digit problems. The 2-digit addition problems required a
trade from the ones (27+57 and 54+19), and the 3-digit problems required a
trade from the tens (571+293 and 284+681); the subtraction problems were the
inverse of the addition problems.
Results
Fewer LMAs than HMAs had a solid understanding of
place value. In the fall, only 26 (70%)
LMAs answered that "1" in 16 was worth of "ten" instead of
one, whereas 36 (97%) HMAs answered correctly without a prompt. Five LMAs needed further prompts by the
researcher ("Is this a 10 or a 1 ?") to be able to come up with the
right answer. However, 6 LMAs were too
adamant to change their answer even after the prompt. In the winter, still 1 LMA answered incorrectly and 2 LMAs needed
a prompt, while all HMAs answered correctly.
LMAs were as accurate as HMAs in
solving mental math problems with totals in the teens when there was no time
constraint. However, more LMAs adopted
a less efficient strategy to solve the problems, such as finger counting or
"counting on" methods. For
the addition problem (8+7), there was a significant difference in the strategy
use for the two groups (see Table 1).
Nineteen (26%) LMAs, but only 3 (4%) HMAs used the less sophisticated
and slower procedures, especially counting.
More HMAs than LMAs (27 vs. 16) adopted more sophisticated and faster
procedures (many used the "make-a-ten" methods). Methods 4 to 6 were not emphasized in class
and more HMAs than LMAs used these methods (7 vs. 1). Additionally, fewer LMAs than HMAs rapidly retrieved the answer
rather than using a solution method (2 vs. 7).
However, the groups did not show significant differences in solving the
subtraction problem (14-6) (see Table 2).
Interestingly, most students in both groups commonly used the
“make-a-ten” method to solve this problem.
For both 2-digit and 3-digit
problems, LMAs did significantly worse than the HMAs in the addition but not in
subtraction problems (see Table 3).
Discussion
First, Chinese LMAs' place-value
concept was less mature and took longer to develop than did that of the
HMAs. Although they did read any
2-digit numbers with the Chinese words "ten something" (42 as
"four ten two"), the verbal label "ten" did not necessarily
create an automatic "magic" for all Chinese children to be aware of
the meaning of the word in relation to the place value of that number and
understand the number sense (e.g., embeddedness of number relations). The result supports the notion proposed by
Vygotsky that psychological functioning occurs first in the inter-personal
level and then gradually shifts to the intra-personal state. Although the Chinese number words correspond
well with the Arabic number system, it is only through the enculturation
process that Chinese children would gradually come to understand the link
between the language (number words) spoken and the object meaning of the
base-10 place value of the number system used in the society. It is a gradual process, and LMAs seem to
need more time than their high-achieving peers to develop this concept. Thus, the gap Ho and Fuson (1998) identified
in Chinese kindergarten children between those who understood the ten in teen
numbers and those who did not is not closed by grade 2. This suggests that LMAs may need to be
provided more and longer explicit teaching before their place-value concept is
consolidated.
These
subtraction-superior-performance findings seem to contradict the common
assumption that subtraction is more difficult and error-prone (e.g., Fuson,
1984). Based on the analyses of strategy data, I propose a "linguistic and
visual support" model to justify this unusual finding (see Table 4). In the process of solving the subtraction
problem, the base-10 structure is explicitly accessible via both visual and
linguistic supports. In 14-6, the
thinking procedure would be: ten minus six, four; four plus four, eight. “Ten” is first seen within and read for the
ten four (14), which then sustains and connects linguistically and visually
with the make-a-ten method. However,
such supports are less transparent in the addition problem. If 8+7 is solved by a "make-a-ten"
method, the procedure will be as: eight plus two, ten; ten plus five, ten
five. The base-10 linguistic support is
less clear (it must be generated during the solution) along with no visual
base-10 support in this case.
The educational implications of this
study are as follows. First, given
adequate supports, especially in both linguistic and visual domains, it is
possible for Chinese LMAs to do as well as their HMA peers. This finding is encouraging because it
suggests that given the right scaffolding, children can learn to SEE and HEAR
and BE AWARE of patterns, structures, and relationships, and then use these as
tools to solve problems. This echoes
the Standards 2000 of NCTM (2000) for how to learn and teach children math. Second, following this paradigm, the
question of whether children use a less regular number system or not seems not
as important as asking the question: “How do we use (linguistic) support to
help our children learn and do math?”
Finally, as Vygotskiian theory indicates, "...we are empowered as
well as constrained in specific ways by the mediational means of a
sociocultural setting" (Wertsch, 1992, p.42). Thus, teachers should be aware of potential means of support when
teaching children in math or any subject.
References
Fuson, K.C. (1984). More
complexities in subtraction. Journal for Research in Mathematics
Education, 15(3), 214-225.
Fuson, K.C. (1988). Children's
counting and concepts of number.
NY: Springer Verlag.
Fuson, K.C., & Kwon, Y.
(1992a). Korean children's single-digit
addition and subtraction: numbers structured by ten. Journal for Research in
Mathematics Education, 23(2), 148-165.
Fuson, K.C., & Kwon, Y.
(1992b). Korean children's
understanding of multidigit addition and subtraction. Child Development, 63, 491-506.
Ho, C.S. & Fuson, K.C.
(1998). Effects of linguistic
characteristics on children’s knowledge of teens quantities as tens and ones:
Comparisons of Chinese, British, and American kindergartners. Journal of Educational Psychology, 90,
536-544.
National Council of Teachers
of Mathematics (2000). Principles and standards for school
mathematics. Reston, VA: NCTM.
Stevenson, H. & Stigler,
J. (1992). The learning gap. New York,
NY: Touchstone.
Vygotsky, L.S. (1978). Mind
in society: The development of higher psychological processes. In M. Cole, V. John-Steiner, S. Scribner,
& E. Souberman (Eds.), Cambridge, MA: Harvard University Press.
Vygotsky, L.S. (1986). Thought
and language. Cambridge, MA: MIT
Press.
Wertsch, J. & Bivens, J. (1992). The social origins of individual mental functioning: Alternatives and perspectives. The Quarterly Newsletter of the Laboratory of Comparative Human Cognition, 14(2), 35-44.
TABLES
Table 1
|
Category |
I |
|
|
II |
|
|
|
III |
|
I |
II |
III |
|
Methods |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
Subtotal 1** |
Subtotal 2-6** |
Subtotal 7-9** |
|
HMAs N= 37 |
7 |
16 |
4 |
4 |
1 |
2 |
3 |
0 |
0 |
7 |
27 |
3 |
|
LMAs N= 37 |
2 |
15 |
0 |
0 |
0 |
1 |
16 |
2 |
1 |
2 |
16 |
19 |
|
Total |
9 |
31 |
5 |
3 |
1 |
3 |
19 |
2 |
1 |
9 |
43 |
22 |
Notes: Category I means “Automatic Procedures”: 1) direct retrieval.
Category II means “More Sophisticated and Faster Procedures”: 2) making the big number ten; 3) making the small number ten; 4) Chinese imaginary abacus method; 5) finger abacus method; 6) doubles.
Category III means “Less Sophisticated and Slower Procedures”: 7) finger counting on from the big number; 8) finger counting on from the small number; 9) counting all.
** means a significant difference between HMAs and LMAs on a c2 test at p <0.01.
Table 2
Frequencies of Use of
Different Strategies for Solving 14-6
|
Category |
I |
|
|
II |
|
III |
IV |
I |
II |
III |
IV |
|
Methods |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
Subtotal 1 |
Subtotal 2-5 |
Subtotal 6 |
Subtotal 7 |
|
HMAs N= 37 |
0 |
27 |
3 |
4 |
2 |
1 |
0 |
0 |
36 |
1 |
0 |
|
LMAs N= 37 |
1 |
30 |
4 |
0 |
0 |
1 |
1 |
1 |
34 |
1 |
1 |
|
Subtotal |
1 |
57 |
7 |
4 |
2 |
2 |
1 |
1 |
70 |
2 |
1 |
Notes: Category I means “Automatic Procedures”: 1) direct retrieval.
Category II means “More Sophisticated and Faster Procedures”: 2) up over ten; 3) down to ten; 4) Chinese imaginary abacus method; 5) finger abacus method.
Category III means “Less Sophisticated and Slower Procedures”: 6) counting down; Category IV means “Others”: 7) don’t know.
Table 3
Percentage Correct for Written Multi-Digit Problems for the Two Achievement Groups
|
Addition |
HMAs |
LMAs |
Subtraction |
HMAs |
LMAs |
|
26+57* |
100 (0) |
87 (35) |
83-57 |
97 (16) |
89 (32) |
|
54+19# |
100 (0) |
89 (32) |
73-19 |
97 (16) |
92 (28) |
|
571+293** |
97 (16) |
76 (44) |
864-571 |
89 (32) |
78 (42) |
|
284+681** |
95 (92) |
73 (45) |
965-284 |
87 (35) |
76 (44) |
|
Total** |
98 (9) |
81 (31) |
Total |
93 (20) |
84 (32) |
Note: # means a marginal difference on a Fisher's exact test at 0.05 < p <0.10;
*means a significant difference on a t-test at p <0.05;
** p <0.01.
Numbers are in percentage and the numbers in the parentheses are standard deviations.
Table 4
|
|