Unit 3 Day 2: Comparing & Ordering Decimals

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Unit 3: The World of Decimals

Day 2: Comparing & Ordering

Which is a better deal?

Store A

$1.50

vs.

Store B

$1.05

To find out, we need to compare the decimals!

Today's Objectives

Strategy 1: Line 'Em Up!

The best way to compare decimals is to use a place value chart.

Compare 0.7 and 0.55

Ones . Tenths Hundredths
0 . 7
0 . 5 5

Since 7 > 5 in the tenths place, 0.7 > 0.55.

Strategy 2: Annex Zeros

"Annex" just means "to add". You can add zeros to the end of a decimal without changing its value.

This helps make the decimals the same length!

0.7

\(\rightarrow\)

0.70

Now it's easy to see that 0.70 (seventy hundredths) is greater than 0.55 (fifty-five hundredths).

Ordering Decimals

To put several decimals in order, use the same strategies!

Order from least to greatest: 0.8, 0.45, 1.2

Ones.TenthsHundredths
0.80
0.45
1.20

The correct order is: 0.45, 0.8, 1.2

I Do: Compare and Order

Compare

Which is greater, 2.45 or 2.4?

1. Line them up: 2.45 and 2.4

2. Annex a zero: 2.45 and 2.40

3. Compare: 45 is bigger than 40.

2.45 > 2.4

Order

Least to greatest: 0.8, 0.45, 1.2

1. Annex zeros: 0.80, 0.45, 1.20

2. Compare the numbers: 80, 45, 120.

3. Smallest is 45, then 80, then 120.

0.45, 0.8, 1.2

We Do: Let's Try Together

Compare using <, >, or = : 1.5 __ 1.35

Hint: Annex a zero to 1.5

1.50 > 1.35

Order from least to greatest: 0.9, 0.99, 0.09

0.09, 0.9, 0.99

You Do: Practice with a Partner

Try these two problems on your whiteboards.

Problem 1:

Compare using <, >, or =

0.62 __ 0.8

Problem 2:

Order least to greatest:

1.25, 1.5, 1.2

Independent Practice

Try these problems on your own.

Green Level

Which is greater: 0.4 or 0.14?

Yellow Level

Order from least to greatest: 5.2, 5.02, 5.22

Red Level

Three students had a long jump competition. Sara jumped 2.05 meters, David jumped 2.5 meters, and Emily jumped 2.25 meters. List them in order from 1st to 3rd place.

Exit Ticket

On a piece of paper, solve this.

Order the following decimals from least to greatest:

4.5, 4.45, 4.05, 4.54

Unit 3: The World of Decimals

Day 2: Comparing & Ordering Decimals - Notes

Today's Objectives

Strategy 1: Line 'Em Up!

The best way to compare decimals is to use a place value chart. This helps you compare digits in the same place value, starting from the left.

Example: Compare 0.7 and 0.55

Ones . Tenths Hundredths
0 . 7
0 . 5 5

Since 7 > 5 in the tenths place, we know that 0.7 > 0.55.

Strategy 2: Annex Zeros

You can add zeros to the end of a decimal without changing its value. This makes both decimals the same length, which makes them easier to compare.

Example:

0.7 becomes 0.70

Now it's easy to see that seventy hundredths (0.70) is greater than fifty-five hundredths (0.55).

I Do: Teacher Examples

Compare: Which is greater, 2.45 or 2.4?

1. Annex a zero: 2.4 becomes 2.40.

2. Compare 2.45 and 2.40. Since 45 > 40, the answer is .

Order: Least to greatest: 0.8, 0.45, 1.2

1. Annex zeros: 0.80, 0.45, 1.20

2. The correct order is:

We Do: Guided Practice

Compare using <, >, or = :

1.5 1.35

Order from least to greatest:

0.9, 0.99, 0.09 \(\rightarrow\)

You Do: Partner Practice

Compare using <, >, or = :

0.62 0.8

Order from least to greatest:

1.25, 1.5, 1.2 \(\rightarrow\)

Independent Practice

Green: Which is greater: 0.4 or 0.14?

Yellow: Order from least to greatest: 5.2, 5.02, 5.22.

Red: Sara jumped 2.05m, David jumped 2.5m, and Emily jumped 2.25m. List them in order from 1st to 3rd place.

Exit Ticket

Order the following decimals from least to greatest:

4.5, 4.45, 4.05, 4.54