As you watch the video, consider the following questions. You might want to take
notes on what you notice.
- How is the teacher using this as an assessment and teaching opportunity?
- How does she structure this sharing of strategies?
- What questions does she ask?
- What statements does she make?
Using assessment to inform decisions about teaching is an essential part of help-
ing students who are struggling in mathematics. Looking at students’ work on
formal assessments can be useful, but observing students and asking them ques-
tions as they do activities that have not been labeled as assessments can be even
more informative. The more specifically a teacher can figure out what aspects of
mathematics concepts or skills a student is struggling with, the better the teacher
can decide what to focus on with the student and the class, how to support the
student’s participation in whole-group discussions as well as individual work, and
how to perhaps modify an activity to fit a student’s needs while still addressing the
important mathematics in the activity.
Examining the Video Footage
In the first interview, Ana Vaisenstein explains that in this lesson she “wanted to
assess what kinds of strategies the children were going to use independently for a
subtraction problem. We had been working on subtraction for a while, then we
stopped and did something else. So I wanted to see how much they kept from
what they had been doing.” She chooses Carlos and Kassandra to share first be-
cause they both got correct answers, she thought the other students would un-
derstand their strategies, and she “wanted those responses to be there as points of
reference for the future discussion.”
Carlos uses a “subtracting in parts” strategy. To use his strategy to solve the
problem, Carlos needed to know that the problem is a subtraction problem. He
knows he could take away the second number in parts and that he could break up
48 into 40 and 8. He also seems to realize that it can be easier to take away a mul-
tiple of 10 first.
Kassandra uses the U.S. standard algorithm (a “subtracting by place” strategy)
to solve the problem. She also understands that the problem is a subtraction prob-
lem. Through Ana’s questioning about the value of the numbers, we can see that
Kassandra seems to understand that she is using 10 from the 60 to change the 2
to 12 and knows when she does this that she no longer has 60. She is perhaps still
working on the place value of numbers as she seems a little unsure that the 1 in
14 is really 10.
LINKINGASSESSMENT ANDTEACHING