Assign Check-In: Questions 3–5. Student are asked to use their own strategies. When complete, ask students to choose one problem and explain their solution strategy to a partner. Then choose two problems in particular to discuss as a class.
- Who solved this problem using a mental math strategy?
- Who solved it using a strategy like Julia's (expanded form)?
- Who solved it using a number line?
- Who solved it using a different strategy?
Select students to show or tell how they solved the problems. For each of the two problems, have one student share a mental math strategy solution, another share an expanded form solution, and another show how he or she used a number line. Additional students can demonstrate other solution strategies. Provide students with chart paper or an alternate way to display their work.
After students have shared their explanations, ask the class:
- Which strategy is the easiest to use to solve this problem? Why?
- Which strategy is the quickest, or most efficient? Why?
- Is one of the strategies difficult to use to solve this problem? Why?
- How do you know if a strategy is a good one for you to use? (Answers will vary. Possible response: A good strategy helps me get the right answer, doesn't have a lot of steps, is easy for me to use, and helps me solve the problem quickly and efficiently.)
Use Check-In: Questions 3–5 on the Use Tens and Ones pages in the Student Activity Book to assess students' progress toward representing and solving addition problems using number lines [E2]; applying place value concepts [E1]; and using mental math strategies or paper-and-pencil methods to add [E3, E4].
Use the Workshop in Lesson 6 to provide targeted practice.
