Week 4: Subtraction and Addition

On Tuesday the 29th we worked out of our classroom activities booklet on pages 51-55 (handwritten) using 100s, 10s, and 1s number blocks, index cards, dice, and manipulatives.

Since the number blocks and the index cards were already created we worked on activities 2 through 5.

In activity 2 we used dice to determine the amount of base ten blocks we would use to make two three-digit numbers. After rolling the dice we would create the number by using the correct amount number of blocks. If it was possible your group could exchange the amount of 1s, 10s, or 100s to make an easier total of blocks (similar to exchanging money). Once the numbers were established in their simplest form we wrote a number sentence to compare the two words. An example would be 445 < 569.

In activity 3 we used the same base 10 blocks to do addition. First we picked out two different three-digit numbers and represented them in the blocks. After forming the numbers in blocks we combined the numbers by combining the blocks and exchanging them to create a simple answer. All the steps and diagrams were recorded on a piece of paper we would later turn in.

In activity 4 we did a more abstract activity by using single manipulative pieces to represent numbers instead of a more concrete form with the base 10 blocks. Using the index cards to create the two three-digit numbers we expressed them by placing the correct number on of manipulatives onto a place value mat. Once placing the correct amount we exchanged the manipulatives to create the sum.

 

 

 

In activity 5 we did the same process of creating two three-digit numbers and adding them together but this didn't involve any form of manipulatives by using two different addition techniques; Addition without Regrouping and addition with regrouping (also known as stacking and borrowing).

Addition without Regrouping:

Addition with regrouping:

 

On Thursday the 31st we looked at solving an addition and a subtraction problem using multiple techniques to solve each.

 

 

Our first problem was an addition problem, 34 + 28 = 62. Here are five examples to solve this problem.

 

 

Traditional:

Give & Take:

 

 



 

Partial Sums / Instructional Algorithm:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Compensating:



 

Decomposing:

 

Our second problem was a subtraction problem 52 - 37 = 15. There are six examples to solve this problem.

 

Traditional:



 

Partial Differences:

 

Compensating:

 

 

Distance:

 

Decomposing:

 

Holy Shift:

 These techniques are important to remember for set 3 in our homework which is due soon. Stay tuned for next week's blog and go Cougs!