## Unit 2: Estimation and Computation

Unit 2 Family Letter

## Required Study Links
2.2
2.3 2.4 2.6 2.7 2.8 2.9 2.10 |
Here are some useful websites for unit 2... Learn-2-Learn: Unit 2 EM Resources -See Unit 2 Decimal Squares Interactive Games Mental Math: Decimals Model Decimals: Tenths and Hundredths Decimals: Thousandths AAA Math: Addition of Decimals E-Lab: Adding Decimals Adding and Subtracting Decimals Subtracting Decimals Multiplying Decimals Multiplying Decimals: Demonstration |

## 2.1 Estimation

Why is estimation important? Can you think of real life examples where estimation might be helpful?

Here are a sample of my notes. Your notebook should look similar to this.

## 2.2: Addition of Whole Numbers and Decimals

## 2.3: Subtraction of Whole Numbers and Decimals

Counting-up: Think back to kindergarten. When you wanted to know the difference between 6 and 9, you would likely count-up: (from 6). . . 7, 8, 9. . . probably on your fingers. We can do the same with larger numbers.

For instance, to find the difference between 27 and 132 we can begin at 27 and count up to 132 (using convenient or friendly numbers as much as possible). Let's estimate first 130-30=____

27 (let's add 3 to get it up to 30, a nice round number) +3

30 (why don't we add 70, then we'll be at 100) +70

100 (we need 32 more to be at 132) +32

So, we added all of the numbers on the right or . . . 105

Which means that 132-27=105.

Let's check: 105

+ 27

100

20

+ 12

132

For instance, to find the difference between 27 and 132 we can begin at 27 and count up to 132 (using convenient or friendly numbers as much as possible). Let's estimate first 130-30=____

27 (let's add 3 to get it up to 30, a nice round number) +3

30 (why don't we add 70, then we'll be at 100) +70

100 (we need 32 more to be at 132) +32

So, we added all of the numbers on the right or . . . 105

Which means that 132-27=105.

Let's check: 105

+ 27

100

20

+ 12

132

Here is some extra practice for 2.3: Make and Break Apart

## 2.4: Addition and Subtraction Number Stories

Number stories help us to better understand how we use math in real life.

Here is some extra practice for 2.4: Writing Open Number Sentences

## 2.5: Estimate Your Reaction Time and Landmarks

Can you find the median, mean, mode, minimum, maximum, and range of a set of numbers? We call these landmarks. You can also find the definition for each of these terms, as well as examples, in your SRB.

## 2.6: Chance Events

What is the probability of an event happening?

Can you talk about probability using terms such as,

"It is

Practice converting fractions, decimals, and percents.

ex:

Can you talk about probability using terms such as,

"It is

**likely**that..." or "There is a**20% chance**that..."Practice converting fractions, decimals, and percents.

ex:

**1/2**-->**0.50**-->**50%**Here is some extra practice for 2.6: Making Spinners

## 2.7: Estimating Products

Here is some extra practice for 2.7: Extended Facts

## 2.8: Multiplication of Whole Numbers and Decimals

Here is some extra practice for 2.8: Model the Partial-Products Method

## 2.9: Lattice Multiplication

Here is some extra practice for 2.9: Lattice Multiplication

## 2.10: Comparing Millions, Billions and Trillions

Here is some extra practice for 2.10: Number Stories and Estimation

## Traditional Multiplication

## Unit 2 Vocabulary

algorithm
ballpark estimate certain column-addition method difference digit estimate expanded notation false number sentence impossible lattice method magnitude estimate maximum mean (average) median minimum minuend mode number sentence |
open number sentence
operation symbol partial-differences method partial-products method partial-sums method place place value Probability Meter range reaction time relational symbol sample solution stimulus subtrahend trade-first method true number sentence value variable |