Snack Shop Addition

Est. Class Sessions: 2

Summarizing the Lesson

Display the following problem:

55¢

79¢

85¢

+ 99¢

Ask:

What strategy or tools could you use to solve this problem?

Discuss students’ ideas. If they do not suggest it, remind students that a calculator is one of the many tools available to solve problems. To solve this multiple addend problem, it may be an appropriate choice. Stress to students that a calculator is not always correct and that you have to know what a reasonable answer will be before you use a calculator.

Ask:

Before you solve the problem, how can you estimate the sum? (Possible response: I think the sum will be about $3.00. 99¢ is almost a dollar and 79¢ and 85¢ are close to a dollar, but not quite. Adding 55¢ will bring the total closer to $3.00.)

Have students use the calculator to solve the problem.

Compare the estimate to the sum that your calculator displays. Is it reasonable? (The sum the calculator shows is $3.18, so if the estimate and the sum are close, the sum seems reasonable.)

Assign Questions 7–9 in the Oops, I Spilled the Juice section of the Snack Shop Bills pages in the Student Activity Book to student pairs. Encourage students to use any strategies or tools, including calculators, to find the two missing addends on the page. Some students may see this as an addition problem and others may solve it as a subtraction problem. Either is acceptable.

Upon completion, display and direct students to the Addition Strategies Menu in the Student Activity Book Reference section and ask:

In this unit, we have talked about many ways to solve addition problems. What are your two favorite ways and why?

Assign the Many Ways to Solve a Problem page in the Student Activity Book for students to complete individually. Provide access to 200 Charts, desk number lines, base-ten pieces, and the strategies menu.

Use the Many Ways to Solve a Problem page and the Feedback Box in the Student Activity Book to assess students’ abilities to add two-digit and three-digit numbers using mental math strategies [E3]; add two-digit and three-digit numbers using paper-and-pencil methods [E4]; estimate sums using mental math strategies [E7]; choose good tools and strategies [MPE2]; check for reasonableness [MPE3]; and show work [MPE5].

Use the Midyear Test to assess the expectations in Units
1–7. See Figure 3.

Adventure Book:

Student Activity Book: 378 379 380

Answers