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 likely that..." or "There is a 20% chance that..."
Practice converting fractions, decimals, and percents.
ex: 1/2 --> 0.50 --> 50%
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 |