Subtraction Strategies Menu. There are many benefits to
introducing a strategies menu. The Subtraction Strategies
Menu presents a variety of strategies for students to use.
They are displayed in a way in which they are all perceived as
equal in status—one strategy is not better or worse than
another. Students are able to choose which strategy makes
sense to them. Students may not be able to know exactly
which strategies are most efficient, but a menu allows them
to begin to think about which strategy is better for certain
situations.
Refer to the Subtraction Strategies Chart from Lesson
2 as you remind students that they have an extensive
list of addition strategies. They can also add the two
paper-and-pencil methods, expanded form and compact.
Display and direct students to the Subtraction Strategies Menu page in the Student Activity Book. See
Figure 4 and the Content Note. Go through the example
problems on the menu. Tell students to compare
the menu to the strategies they collected on the chart.
- Are there strategies on the menu that are not on our chart?
- Are there any strategies missing that you would like to add?
- Which of these can you do in your head? (Finding Friendly Numbers, Counting Up, or Counting Back)
- How can you see that they are mental math strategies on the menu? (They are marked with a cloud.)
- Which of these strategies use steps? (Using Base-Ten Pieces, Using Expanded Form, and Using the Compact Method)
- Do you have any questions about a strategy?
Have students remove the Subtraction Strategies Menu from the Student Activity Book
and, if they choose, add strategies not represented to the back of the menu.
Assign the Use Subtraction Strategies pages in the
Student Activity Book for students to complete individually.
Encourage students to use the Subtraction
Strategies Menu and the class’s Subtraction Strategies
Chart as they work. Provide access to base-ten pieces.
Remind students to estimate the sums first so they can
check the reasonableness of their answers.
Use the Use Subtraction Strategies pages and the Feedback
Box in the Student Activity Book to assess students’ abilities
to use and apply place value concepts to make connections
among representations of multidigit numbers using base-ten
pieces and standard form [E1]; subtract multidigit numbers
using mental math strategies (e.g., composing and
decomposing numbers, counting up) with number lines, a
200 Chart, and base-ten pieces [E3]; subtract multidigit
numbers using paper-and-pencil methods (e.g., expanded
form, compact) [E4]; and estimate differences using friendly numbers [E5].
