3.3 Why the Standard Algorithms for Addition and Subtraction in Base Ten Work CA-67 SECTION 3.3 CLASS ACTIVITY 3-J X Understanding the Standard Addition Algorithm CCSS CCSS SMP3, SMP5, 2.NBT.7, 2.NBT.9 Materials Bundled toothpicks or base-ten blocks would be useful for this activity. 1. Add the numbers, using the standard paper-and-pencil method. Notice that regrouping is involved. 147 + 195 2. If available, use bundled things to solve the addition problem 147 + 195. Make base-ten math drawings to indicate the process you used. 3. If available, use bundled things to solve the addition problem 147 + 195 in a way that corresponds directly to the addition algorithm you used in part 1. This may be different from what you did in part 2. Make base-ten math drawings to indicate the process you used. Compare with part 2. 4. Use expanded forms to solve the addition problem 147 + 195. First add like terms; then rewrite (regroup) the resulting number so that it is the expanded form of a number. This rewriting is the regrouping process. 1(100) + 4(10) + 7(1) + 1(100) + 9(10) + 5(1) First add like terms, remaining in expanded form. Then regroup so that you have the expanded form of a decimal number. You might want to take several steps to do so. 5. Compare and contrast your work in parts 1-4