Ask students to compare the two problems 89 × 11 and 56 × 84.
- Which problem can you solve using mental math? How? (Possible response: 89 × 11 = 90 × 11 - 11 = 990 - 11 = 979)
- Which problem would you rather solve using pencil and paper?
- What paper-and-pencil methods have we studied for solving 2-digit by 2-digit problems? (rectangle method, expanded form, and all-partials method)
Ask students to take out the My Multiplication Menu page from their Student Activity Books. This is a blank menu. Have students develop a multiplication strategies menu for themselves showing multiplication of 89 × 11 and 56 × 84. They draw their own divisions as they choose.
Tell students to include the following:
- a problem using a mental math strategy to find an exact answer
- at least two of the paper-and-pencil methods
- a strategy for finding an estimate using mental math
Encourage them to illustrate their menus and label the strategies. Suggest they leave a space for the compact method, which will be covered in Lesson 4. Students can use the Multiplication Strategies Menu from Unit 7 or in the Student Guide Reference section as an example. Students will need their menus in the next lesson.
Ask students who have trouble beginning the problem in Question 18:
- Which method does the problem ask you to use for sure? (all-partials method)
- Show me an example of the all-partials method in the Student Guide and a problem that you have completed using the all-partials method.
Check to see that students can identify the all-partials method and that they completed problems in Question 16 correctly.
- Which other methods do you have to choose from? Show me examples of those methods in your Student Guide. (Using rectangles and expanded form)
- Which one do you want to use?
For students who struggle to explain how the methods are alike and different in writing, ask them to tell you in their own words. Use prompts similar to the following:
- How are the problems alike? Are any of the numbers the same? Which ones?
- What numbers did you multiply in each method?
- How are they different? Did you write something in one that you did not in the other?
Have students complete the Multiplication Quiz 1 pages from the Teacher Guide.
Use the Multiplication Quiz 1 Assessment Master and the corresponding Feedback Box to assess multiplication concepts covered in Lessons 1 and 2 including: demonstrating understanding of the place value concepts and mathematical properties involved in multiplication of 2-digit by 2-digit numbers [E1]; estimating products of multidigit numbers [E3]; multiplying 2-digit by 2-digit numbers using mental math strategies and paper-and-pencil methods [E4]; and choosing appropriately from among estimation, mental math strategies, and paper-and-pencil methods to multiply whole numbers [E6].
Use student responses and the corresponding Feedback Box to guide your instructional decisions for the targeted practice for Expectations 1, 3, and 4 in the Lesson 3 Workshop.
