Adding and SubtractingWhole Numbers

Unit of Study: 5Global Concept Guide: 4 of 4

Content DevelopmentStudents should grow comfortable solving addition and subtraction problems using numbers through hundred thousands (6-digits).

Build conceptual understanding of regrouping. Avoid simply showing the algorithm before regrouping is understood and avoid using the term “borrow”.

Make sure to teach addition and subtraction together showing they are inverse operations, not teaching each in isolation.

Provide students with multiple opportunities to use large numbers in both story problems and tables when adding and subtracting.

Day 1 Students should be able to create models to show addition and

subtraction problems. Use both base-ten blocks and drawing to model numbers.

Example:

Lucy represented the number1,234 with in a written model. Ming drew a similar model representing the number 1,355. What is the sum of their models?

Day 2Make sure to provide opportunities for students to conceptually understand regrouping. Allowing students to use base-ten blocks to model regrouping , helps them build understanding.

Avoid simply showing the algorithm before regrouping is understood.

Provide students with real world problems to practice regrouping.

6

354+ 78

12314

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124- 78

1 14

6

011

4

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Day 3 and Day 4 Make sure to teach addition and subtraction together and not in isolation. When using strategies for addition and subtraction start with 4-digit

numbers and use this to build into numbers through hundred thousands. Provide opportunities for students to see multiple strategies when

adding and subtracting larger numbers:

674- 328

674 -300

374 - 20

354 - 4

350 - 4

346

Break Apart Strategy (Decomposing)- numbers written in expanded form and each place value is added or subtracted

Place Value Method- The most common way to add and subtract going digit-by-digit with in the number.

300 + 20 + 8 = 328

Day 5 Students should be able to apply the most efficient strategy when solving

problems.

Student’s should make the connection that addition and subtraction are inverse operations.

Provide students with facts and solutions and have them identify the question and/or operation that could be used to arrive at the solution.

Example:Facts-There are 7,700 lakes in Florida. There are 4,500 lakes in Michigan. Solution- 3,200 lakes

What question could be asked to get this solution, and what operation was used?

Enrich/Reteach/Intervention Reteach/Intervention: Using a selection of problems and have

students make numbers with base-ten blocks and have them model regrouping. Allow student to become successful with modeling and move to pictoral representations.

If student’s are struggling with the alignment of digits when adding or subtracting, have students utilize grid paper to keep the digits within the correct place value position. (Hint: Students can also turn notebooks side ways providing columns for this as well)

Enrich/Reteach/Intervention

Enrich- Give students riddles (CPALMS lesson found on GCG) and have them use the clues to discover the number. Also have students create their own riddles when given a number.