Problem Solving

Supportingchildren’s
problem
solving

98 September 2010 • teaching children mathematics www.nctm.org
Copyright © 2010 The National Council of Teachers of Mathematics, Inc. www.nctm.org. All rights reserved.
This material may not be copied or distributed electronically or in any other format without written permission from NCTM.

Teachers demonstrated four
categories of reasoning when
deciding how to respond to students.

“H
elp! I’m stuck!”
How m a n y
times have you
heard a student
make a similar plea? What do you
consider when deciding how to
respond? What reasoning is most
productive?
As part of a large research proj-
ect, we explored these questions with
131 prospective and practicing teach-
ers and found patterns in their reasoning.
Consider how teachers and professional
developers can use these patterns to better sup-
port children during problem solving.

The video
We began our project by sharing a video of a
one-on-one conversation that took place in June
between a teacher and Rex, a kindergartner. (See
fig. 1 for the three problems discussed. View the
three-minute video at www.nctm.org/tcm/. We
encourage you to view the video before reading
the rest of this article, but if that is not possible at
the moment, please read the video transcript in
the appendix on p. 105 before continuing.) The
video ends when the teacher poses the tadpole
By Victoria R. Jacobs and Randolph A. Philipp problem and Rex comments, “I don’t even know
that one. That’s hard.”
Marcela Barsse/iStockphoto.com

How might you respond to Rex, and why
would you choose that response?

Four responses
After we showed this video, we posed the same
question to the teachers in our study. When
you read the four samples of written responses

www.nctm.org teaching children mathematics • September 2010 99

Three problems were posed to Rex. beyond his ten fingers. Considering this, I

Figu r e 1
think the third problem caused some difficulty
1. Rex had thirteen cookies. He ate six of because he couldn’t represent fifteen tadpoles
them. How many cookies does Rex with his fingers. Also, since his other strategies
have left? involved counting on and counting back, he
2. Today is June 5, and your birthday is might think he could use that here.
June 19. How many days away is your OK, the original question, what to do from
birthday? here: I’d start by asking him why that problem
3. Rex had fifteen tadpoles. He put three
was hard. Is it because of the language and
tadpoles in each jar. How many jars did
context of tadpoles? Is it because he can’t use a
Rex put tadpoles in?
counting on or back strategy? Does he recognize
that his previous counting strategies won’t work?
Where I’d go from there would really depend
on his response. I’m going to assume that he
below, think about how your own proposed understands what the problem is asking. I might
response compares with theirs. In particular, if adjust the numbers to sixteen and two to see if
you had to choose the sample response most he’d skip count by twos up to sixteen and keep
similar to yours, which would it be? track on his fingers. If Rex explained that it was
hard to use his fingers for this one, I might ask if
Response 1: I would help him draw a picture there’s another tool that would help him.
and guide him through the problem. I would ask
him to draw fifteen dots or lines to represent the Response 4: I would ask him what he knows
fifteen tadpoles. Then I would tell him that there about the problem, or what the story tells us,
will be three in each jar, so to represent each and what we’re trying to find out. Then I would
jar, he could circle tadpoles in groups of three. I have him start with what he knows and build
would then ask him how many circles he has. from there. I would ask questions along the way
Another method I would guide him through as a guide to get him started. I think questioning
would be to use the cubes that were on the table. is a way to guide students in the process of how
I would ask him to count out fifteen cubes and to start and where to go next.
then make them into sticks of three (stick them
together). I would then ask him to count how Children’s mathematical
many sticks he has. thinking
The range of goals and teacher moves proposed
Response 2: I might say something like, “Yes, in these responses highlights the inherent ambi-
that does seem a little bit harder than our last guity in teaching—a teacher must always choose
problems, but you’re a smart boy. I’m sure if among multiple paths when supporting a child
we work together, we could solve it.” I’d agree during problem solving. We were not expect-
with him that it’s a difficult problem—to let him ing teachers to describe any particular path for
know I understand how he feels. I’d use positive working with Rex, and all four sample responses
reinforcement by telling him I think he’s smart contain pieces to appreciate. However, because
to boost his confidence. I’d offer to work on the research has shown the power of paying atten-
problem with him because he obviously needs tion to children’s mathematical thinking, we
help. I believe after solving the problem together, were particularly interested in the role that chil-
Rex would feel very proud of himself. dren’s mathematical thinking played in teachers’
decision making: Did teachers use what they
Response 3: Rex really prefers to use his fingers learned about Rex’s mathematical thinking on
as a tool to solve problems. In the first problem the first two problems when deciding how to
he used them to count down from thirteen, respond? Did their instructional suggestions
keeping track of when he’d counted down six leave space for Rex’s future thinking?
times. In the second problem, he counted on Children often have ways of thinking about
from June 5 to June 19, but was thrown—ever mathematics that differ from adult ways, and
so slightly—when his counting on continued research has shown that instruction that builds


on children’s ways of thinking can lead to rich
instructional environments and gains in stu-
dent achievement (NCTM 2000; NRC 2001).
However, creating these instructional envi-
ronments has proven challenging, par-
ticularly because this vision of instructing
requires that teachers keep children’s
mathematical thinking central when mak-
ing in-the-moment decisions that occur
hundreds of times a day. Specifically, to
use children’s mathematical thinking
when deciding how to respond, teachers
must not only detect children’s ideas that
are embedded in comments, questions, nota-
tions, and actions but also make sense of what
they observe in meaningful ways. We focused
on teachers’ use of children’s mathematical
thinking in deciding how to respond to children
who need support during problem solving. Note
that equally challenging is the decision mak- • bility to successfully solve two problem
A

Marcela Barsse
ing required to extend children’s mathematical types—Rex answered a subtraction problem
thinking after they have successfully solved a and a missing-addend problem.
problem (Jacobs and Ambrose 2008–2009). • ange of counting strategies—Rex counted
R
up on the birthday problem and counted
Rex’s thinking down on the cookie problem.
What did we learn about Rex’s mathematical • merging understanding of tens—On the
E
thinking? At first glance, we learned that this birthday problem, he was able to think of
five-year-old successfully solved two problems ten as a group: After he had counted to June
by counting on his fingers before deciding 15 and had ten fingers extended, he paused
that the third problem was too difficult. We and said, “That’s ten,” before continuing
wondered what else we could have learned. his counting to June 19. He was then able to
Research on children’s mathematical think- conserve ten in his head and count on to the
ing has shown that paying attention to the answer of fourteen by recounting the four
details of children’s strategies matters because extended fingers.
these details provide a window into children’s • reference for using his fingers as a tool—
P
understandings—information that teachers Although other problem-solving tools (e.g.,
can use to decide their next instructional steps cubes) were available, Rex chose to use his
(Carpenter et al. 1999). By attending closely fingers on both problems that he solved.
to the details of Rex’s problem solving on the
cookie and birthday problems, we could learn The next steps
the following, for example, about his thinking: How might these details inform instructional
next steps? The tadpole problem is a mea-
• illingness to try to solve both problems—
W surement-division problem in which the total
When Rex had difficulty, he was willing to number and size of each group is provided, but
continue working. For instance, Rex imme- the number of groups is unknown. Research
diately began engaging with both problems has shown that measurement-division prob-
and, on the birthday problem, after declaring, lems are accessible to young children and not
“I can’t figure that one out,” he was willing and substantially more difficult than problems with
able to proceed after the teacher offered only the mathematical structures of the first two
minimal assistance. In short, Rex displayed problems. Because Rex correctly solved the first
a productive disposition (NRC 2001) toward two problems using counting strategies with
solving problems. his fingers, we can reasonably assume that he


should be able to solve the tadpole problem with strategies for the tadpole problem—strategies
either a counting strategy or a less sophisticated that were consistent with Rex’s existing strate-
strategy in which all the tadpoles would be rep- gies and the research on children’s mathemati-
resented and distributed into jars. If Rex chose cal thinking.
this less sophisticated strategy, he might need In the first paragraph of her response, this
a tool other than his fingers (e.g., cubes) so that teacher showed that she had carefully attended
he could represent all fifteen tadpoles and place to how Rex had solved the first two problems.
them in groups of three (Carpenter et al. 1999). Details she highlighted included Rex’s facil-
We recognize that attending to and reasoning ity in and preference for using his fingers, his
about the details of Rex’s mathematical thinking counting-up and counting-down strategies, and
does not prescribe a specific response, nor do his emerging base-ten understanding. She then
we believe that there is a single best response. used her observation that Rex was thrown “ever
However, we do believe that teachers can use the so slightly” when the numbers went beyond ten
types of details described above to inform their in the birthday problem to hypothesize why Rex
instructional next steps so that they are likely to might be struggling with the tadpole problem
make the mathematics accessible to children (“he couldn’t represent fifteen tadpoles with his
and ensure that the children (not the teachers) fingers”). Note that the teacher’s reasoning is
do the mathematical thinking. Thus, when read- not generic reasoning about a division problem
ing the teachers’ responses, we looked for two but, instead, is particular to how she thinks Rex
characteristics: First, did the teacher attend to might engage with the tadpole problem on the
the details of Rex’s mathematical thinking on basis of what she learned from his mathematical
the first two problems? Second, did the teacher’s thinking on the previous two problems.
instructional suggestions build on Rex’s think- In the second paragraph, she focused on
ing on the first two problems and leave space for problem difficulty (“asking him why that prob-
Rex’s future thinking? lem was hard”), leaving space for Rex’s thinking
while considering connections to his past work

TM_Design/iStockphoto.com
A focus on Rex’s thinking (“Is it because he can’t use a counting-on or
We found that only one sample, response 3, [counting]-back strategy? Does he recognize that
focused on Rex’s mathematical thinking. The his previous counting strategies won’t work?”).
teacher who gave this response not only con- She then explicitly stated that her next steps
sidered what she had learned about Rex’s math- “would really depend on his response,” indicating
ematical thinking on the first two problems but that Rex’s thinking would play a prominent role
also anticipated possible


in the proposed interaction. She acknowledged
the importance of ensuring that Rex understood Reasoning that teachers use
the problem and then continued by proposing a Distinguishing among these four categories of reasoning that teachers use when
variety of possible supporting moves, all of which deciding how to support a student during problem solving can serve as a self-
were consistent with what the video showed reflection tool for teachers and a reflection tool for professional developers:
about Rex’s mathematical thinking. For example,
1. The child’s mathematical thinking
she suggested changing the problem numbers
(to sixteen tadpoles distributed into jars of two 2. The teacher’s mathematical thinking
tadpoles each) making the skip counting easier 3. The child’s affect
(twos instead of threes) to facilitate Rex’s use of a 4. General teaching moves
familiar counting strategy while still enabling the
use of a familiar tool (i.e., Rex could use each fin-
ger to represent two tadpoles and thus count by The teacher’s thinking
twos to sixteen without having to count beyond Response 1 illustrates a focus on the teacher’s
his two hands). mathematical thinking. This teacher suggested
Although we found this teacher’s suggestions two specific and effective strategies for solving
to be interesting moves for supporting Rex, we the tadpole problem, and these strategies are
recognize that there are many other helpful moves ones that children are likely to use. However, in
that a teacher could have made in response to this case, the strategies are the teacher’s strate-
Rex. Thus, the expertise in this teacher’s response gies, and whether any attention has been (or
depends not on a specific move she suggested would be) paid to Rex’s understandings of these
but instead depends on her consistent and exten- strategies is unclear. In general, teachers who
sive consideration of Rex’s mathematical thinking focused on their own mathematical thinking did
on the previous problems as well as her attention not build on Rex’s past thinking and, in particu-
to the importance of his future thinking in solving lar, did not create space for his future thinking.
the tadpole problem. Instead, they generally emphasized reach-
The next section explores the other three ing a correct answer and suggested guiding
sample responses, in which teachers did not Rex—step by step—through the solving of the
focus on Rex’s mathematical thinking. tadpole problem.
Teachers with responses in this category did
Alternatives not build on children’s mathematical thinking,
We identified three categories of responses that but they did provide explicit details about strate-
did not focus on Rex’s mathematical thinking. gies. As illustrated in responses in the next two
Each has important kernels that teachers can categories, not all teachers provided such detail.
use as starting points for incorporating a focus Therefore, this attention to detail is a strength
on children’s mathematical thinking into their and can provide a starting point for teachers
decision making. who want to learn to redirect their attention to
the details of children’s (rather than their own)
mathematical thinking.
The best
Rex’s affect
instructional Response 2 illustrates a focus on Rex’s affect and
lacks the specificity about strategies found in
next steps build on the previous two categories of responses. This
teacher emphasized nurturing Rex’s confidence
students’ strategies and positive feelings but made no reference
to his past or future mathematical thinking.
and leave room Research has connected lack of confidence or
dislike of mathematics with low achievement
for their future (Ma 1999), and thus these affective goals are
important, but they are insufficient for offering
thinking. instruction that builds on children’s mathemati-


cal thinking. Teachers with responses in this to enhance their own decision making about
category can work to augment this affective instructional next steps by continually asking
focus so that they also consider the details of themselves the following questions when a
children’s mathematical thinking when deciding child needs support:
how to respond.
• hich details provide evidence for my con-
W
General teaching moves clusions about what I know of this particular
Response 4 illustrates a focus on general teach- child’s strategies and understandings?
ing moves, again with a lack of specificity about • ow can I build on this child’s existing strate-
H
strategies. For example, this teacher mentioned gies and understandings to give him or her an
the importance of asking questions without entry point to engage with the problem?
articulating specific questions or even types of • ave I left space for this child’s mathemati-
H
questions to be posed (“I would ask questions cal thinking? In what ways? Or did I solve the
along the way as a guide to get him started”). problem for the child?
A defining characteristic of this category was
that the responses were general enough to be R E F E RE N C E S
applied to any problem and any child—nothing Carpenter, Thomas P., Elizabeth Fennema, Megan
in this teacher’s suggestions was customized to Loef Franke, Linda Levi, and Susan Empson.
the tadpole problem or Rex’s thinking. Nonethe- Children’s Mathematics: Cognitively Guided
less, teachers with responses in this category Instruction. Portsmouth, NH: Heinemann, 1999.
often expressed an intention to use Rex’s math- Jacobs, Victoria R., and Rebecca C. Ambrose.
ematical thinking (“I would have him start with “Making the Most of Story Problems.” Teach-
what he knows and then build from there”). ing Children Mathematics 15 (December 2008/
Research has shown how challenging attend- January 2009): 260–66.
ing to and building on children’s thinking is. Ma, Xin. “A Meta-Analysis of the Relationship
Thus having these general goals is an important between Anxiety toward Mathematics and
starting point for teachers who can then work to Achievement in Mathematics.” Journal for
incorporate the details of children’s mathemati- Research in Mathematics Education 30, no. 5
cal thinking into their decision making. (November 1999): 520–40.
National Council of Teachers of Mathematics
Final thoughts (NCTM). Principles and Standards for School
In-the-moment decision making is a hid- Mathematics. Reston, VA: NCTM, 2000.
den, but critical, skill of teaching that needs National Research Council (NRC). Adding It Up: Help-
to be discussed and developed. We want to ing Children Learn Mathematics, edited by Jeremy
underscore the complexity of this skill and Kilpatrick, Jane Swafford, and Bradford Findell.
the challenge in developing this expertise. Washington, DC: National Academy Press, 2001.
To support teachers’ growth, we identified
four categories of reasoning that teachers use This research was supported in part by a
when deciding how to support a child dur- grant from the National Science Foundation
ing problem solving (see sidebar on p. 103). (ESI0455785). The views expressed are those of the
Although we recognize that these foci are not authors and do not necessarily reflect the views of
mutually exclusive, we think that distinguish- the National Science Foundation.
ing among them can serve as a self-reflection
tool for teachers and a reflection tool for Victoria R. Jacobs, vjacobs@mail.sdsu.edu, and
professional developers. Teachers may recog- R
andolph A. Philipp, rphilipp@mail.sdsu.edu, are
nize themselves in each of these categories, mathematics educators at San Diego State Univer-
perhaps in different situations or at differ- sity in California. They collaborate with teachers to
ent times in their own development. We explore children’s mathematical thinking and how
hope that these categories can also indicate that thinking can inform instruction.
paths for future growth toward instruction
View the three-minute video by accessing this
in which children’s mathematical thinking is
article at www.nctm.org/tcm/.
central. To that end, we encourage teachers


➺ appendix

This is a transcript of the three-minute video available online at www.nctm.org/tcm/ with the Jacobs and Philipp
article. Rex, a kindergartner, is working individually with a teacher. Unifix® cubes, as well as paper and pencil, are
available for his use.

Rex had thirteen cookies. He ate six of them. How many OK, how could we use our fingers? What should we do?
cookies does Rex have left? Like this: June 5, June 6—No [raising one finger for June 6 and
[Quietly counting back six from thirteen, putting up a finger then hesitating].
with each count] Seven.
OK, June 6.
And how did you figure that out, Rex? June 7 [continuing to count, raising a second finger for June 7 ].
I counted down with my fingers.
OK, June 6, June 7 [mirroring what Rex has done, putting
OK, tell me how you did that. up two fingers—one for June 6 and one for June 7 ].
I went like, umm, thirteen, and then I went, twelve, eleven, ten, June 8, June 9, June 10, June 11, June 12, June 13, June 14,
nine, eight, seven [demonstrating how he counted back six from June 15 [continuing to count up, putting up a finger with each
thirteen, putting up a finger with each count]. count and stopping when all ten fingers are raised. The teacher
continues to mirror what Rex has done by putting up her fingers
Good. Now, is that how old you are? Are you seven? with each of his counts]. That’s ten.
No.
Uh huh.
Well, how old are you? June 16, June 17, June 18, June 19 [continuing to count up, put-
Five. ting up a finger with each count until four fingers are raised]. It
must be [pausing and quietly recounting the fingers above ten
You’re five? And when is your birthday? by counting on: eleven, twelve, thirteen, fourteen] fourteen days
June 19. away.

It’s coming up pretty soon, isn’t it? Wow! Now, Rex, do you know what guppies are?
And then I’m going to be six. No.

And how many days away is your birthday? If today is Do you know what goldfish are?
June 5, how many days away is your birthday? Yes.
[Quietly counting on his fingers, beyond ten, but after some
counting (and re-counting), stopping] I can’t figure that one Or would you rather do tadpoles?
out. Tadpoles!

Well, let’s see. Today is June 5 and your birthday is June 19, OK. Rex had fifteen tadpoles. He put three tadpoles in each
so what do you think we could do to figure that out? jar. How many jars did Rex put tadpoles in?
Use our fingers or something. I don’t even know that one; that’s hard.


Problem Solving

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