TOPIC 2: NUMBER SENSE: ADDITION AND SUBTRACTION

Domain: Number and Operations in Base 10

3.NBT.1: Use place value understanding to round whole numbers to nearest 10 or 100

3.NBT.2: Fluently add and subtract within 1000 using strategies and algorithms based on place value, properties of operations, and/or the relationship between addition and subtraction

Domain: Number and Operations in Base 10

3.NBT.1: Use place value understanding to round whole numbers to nearest 10 or 100

3.NBT.2: Fluently add and subtract within 1000 using strategies and algorithms based on place value, properties of operations, and/or the relationship between addition and subtraction

## Lesson 2.1-Properties of Addition

Objective:

Students use concrete materials and concepts of addition to model the Commutative, Associative, and Identity Properties of Addition.

Students use concrete materials and concepts of addition to model the Commutative, Associative, and Identity Properties of Addition.

You can use addition to join groups.
ADDENDS are numbers that are being added together. The SUM is the answer when adding. There are 3 Properties of Addition.
Commutative (Order) Property of Addition: You can add numbers in any order and the sum will be the same. For example, 4+8=8+4Identity (Zero) Property of Addition: The sum of zero and any number is that same number. For example, 6+0=6Associative (Grouping) Property of Addition: You can group addends in any way and the sum will be the same. For example, (3+4) +6=13 and 3+ (4+6)=13. Parentheses ( ) show what to add first. |

Look below to watch learning videos and practice the 3 Properties of Addition:

smart_game_commutative_identity.notebook | |

File Size: | 234 kb |

File Type: | notebook |

Lesson 2-2: Subtracting Meanings

Lesson Objective:

Students recognize situations when subtraction is used to solve a problem and write number sentences.

Students recognize situations when subtraction is used to solve a problem and write number sentences.

LESSON 2-3: USING MENTAL MATH TO ADD

Lesson Objective: Students will solve problems by adding with mental math.

When you add using mental math, it means that you find the answer "in your head" without using pencil and paper. Here is an example of you could "break apart" 23+35

LESSON 2-4: USING MENTAL MATH TO SUBTRACT

Lesson Objective:

Students will solve problems by subtracting with mental math.

Students will solve problems by subtracting with mental math.

## LESSON 2-5: ROUNDING

Lesson Objective:

Students will round two-digit and three-digit whole numbers to the nearest ten or hundred, by comparing to the number halfway between or by using place value.

Students will round two-digit and three-digit whole numbers to the nearest ten or hundred, by comparing to the number halfway between or by using place value.

To round, replace a number with a number that tells

There are 2 ways to round:

1. You can use a number line. In the example above, 52 is between 50 and 60. It is closer to 50, so 52 rounds to 50

2. Another way to round is to use place value.

__how many.__*about*There are 2 ways to round:

1. You can use a number line. In the example above, 52 is between 50 and 60. It is closer to 50, so 52 rounds to 50

2. Another way to round is to use place value.

- Find the digit in the rounding place.
- Look at the next digit to the right. If it is 5 or greater, add 1 to the rounding digit. If it is less than 5, leave the rounding digit alone.
- Change all the digits to the right of the rounding place to 0.

jack_and_jill_round-off_hill.notebook | |

File Size: | 641 kb |

File Type: | notebook |

Here are some learning sites to practice rounding numbers:

Math Playground Rounding Learning Video

Mr. Anker Rounding Tests

Seashell Rounding

Rounding Flashcards

Rounding Dartboard Game

LESSON 2-6: ESTIMATING SUMS

Lesson Objective:

Students will solve problems by estimating sums.

Students will solve problems by estimating sums.

LESSON 2-7: ESTIMATING DIFFERENCES

Lesson Objective:

Students will solve problems by estimating differences.

Students will solve problems by estimating differences.

LESSON 2-8: MAKING SENSE OF ADDITION AND SUBTRACTION EQUATIONS

Lesson Objective:

Students will decide whether both sides of an equation are equal and they will determine the value of an unknown number in an equation.

Students will decide whether both sides of an equation are equal and they will determine the value of an unknown number in an equation.

Lesson Vocabulary:

An

**EQUATION**An

**is***EQUATION**a number sentence that uses an equal sign (=) to show that the value to its left is the same as the value to its right*.Here are some examples of equations:

20 + 9 = 29

30 + 12 = 44 - 2

15 = 20 + 5 - 10

Some equations have symbols or letters to represent unknowns. What number does the letter

20 + 9 = 29

30 + 12 = 44 - 2

15 = 20 + 5 - 10

Some equations have symbols or letters to represent unknowns. What number does the letter

*n*stand for in this equation? 7 = n - 8. The subtraction fact that matches this is 15 - 8 = 7, the value of*n*is 15. So,*n*= 15.LESSON 2-9: PROBLEM SOLVING: REASONABLENESS

Lesson Objective: Students will solve word problems and check their answers for reasonableness.

__ADDITION LEARNING VIDEOS:__

__FUN ADDITION LEARNING SITES:__

## FUN GAME!!

SUBTRACTION

Click HERE for a great site to understand SUBTRACTION WITH REGROUPING

KHAN LEARNING VIDEO 1

KHAN LEARNING VIDEO 2 (WITH REGROUPING)

KHAN LEARNING VIDEO 1

KHAN LEARNING VIDEO 2 (WITH REGROUPING)