Decimals: Level Up!

Scott Weber

Tier 1

Lesson Plan

Decimals: Level Up!

Students will be able to confidently add, subtract, multiply, and divide decimals, applying these skills to solve real-world problems.

Understanding decimal operations is essential for everyday tasks, such as budgeting, cooking, and science. This lesson helps students build a strong foundation for future math concepts.

Audience

7th Grade

Time

30 minutes

Approach

Interactive slides, guided practice, and an engaging worksheet.

Materials

Decimals: Level Up! Slide Deck, and Decimal Dynamo Worksheet

Prep

Teacher Preparation

10 minutes

Review the Decimals: Level Up! Slide Deck to familiarize yourself with the content.
- Print copies of the Decimal Dynamo Worksheet for each student.
- Ensure projector/screen is set up for the slide deck.

Step 1

Warm-Up & Introduction

5 minutes

Display the first slide of the Decimals: Level Up! Slide Deck.
- Greet students and introduce the lesson's exciting title: "Decimals: Level Up!"
- Ask students: "Where do you encounter decimals in your daily lives?" (e.g., money, measurements, sports statistics).
- Briefly review the four basic decimal operations: addition, subtraction, multiplication, and division.

Step 2

Guided Practice with Slide Deck

10 minutes

Advance through the Decimals: Level Up! Slide Deck, guiding students through example problems for each operation.
- Encourage student participation by asking them to solve parts of the problems or explain their thinking.
- Address common misconceptions or difficulties as they arise.

Step 3

Independent Practice: Worksheet

10 minutes

Distribute the Decimal Dynamo Worksheet.
- Explain that students will work independently to practice their decimal operation skills.
- Circulate around the room, providing individual support and answering questions.
- Remind students to show their work clearly.

Step 4

Wrap-Up & Review

5 minutes

Briefly review a few problems from the Decimal Dynamo Worksheet as a class, focusing on any areas where students struggled.
- Ask students to share one new thing they learned or one area where they feel more confident.
- Collect the worksheets.

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Slide Deck

Decimals: Level Up!

Ready to master decimals?

Welcome students and introduce the lesson. Engage them by asking where they see decimals in real life.

What Are Decimals?

Decimals are numbers that represent parts of a whole.
They use a decimal point to separate the whole number part from the fractional part.

Briefly review what decimals are and their importance.

Adding Decimals

Rule: Line up the decimal points, then add as you would with whole numbers.

Example:
2.35 + 1.62 = ?

Explain the rules for adding decimals: line up decimal points, add as usual, bring down the decimal point.

Subtracting Decimals

Rule: Line up the decimal points, then subtract as you would with whole numbers. You may need to borrow!

Example:
5.75 - 3.23 = ?

Explain the rules for subtracting decimals: line up decimal points, subtract as usual, bring down the decimal point. Remind students about borrowing if needed.

Multiplying Decimals

Rule: Multiply the numbers as if they were whole numbers. Then, count the total number of decimal places in the numbers you multiplied. Place the decimal point in your answer that many places from the right.

Example:
1.2 x 0.4 = ?

Explain the rules for multiplying decimals: multiply as whole numbers, then count total decimal places in factors to place in product.

Dividing Decimals

Rule: If the divisor is a decimal, move the decimal point to the right until it is a whole number. Move the decimal point in the dividend the same number of places to the right. Then divide as usual, placing the decimal point in the quotient directly above the new decimal point in the dividend.

Example:
6.4 ÷ 0.2 = ?

Explain the rules for dividing decimals: move decimal in divisor to make it a whole number, move decimal in dividend same number of places, divide, bring decimal straight up.

Time to Practice!

Now it's your turn to be a Decimal Dynamo!

Work on your Decimal Dynamo Worksheet independently.

Remember to show your work!

Introduce the worksheet as independent practice.

Worksheet

Decimal Dynamo Worksheet

Instructions: Solve each problem below. Show your work clearly for full credit.

Part 1: Adding Decimals

5.25 + 3.75
12.8 + 7.05
0.67 + 1.3 + 4.25

Part 2: Subtracting Decimals

9.5 - 4.3
15.0 - 8.75
7.24 - 3.8

Part 3: Multiplying Decimals

3.5 x 2.1
0.15 x 0.8
10.3 x 4

Part 4: Dividing Decimals

8.4 ÷ 0.4
12.96 ÷ 1.2
5.6 ÷ 7

Answer Key

Decimal Dynamo Answer Key

Part 1: Adding Decimals

5.25 + 3.75
- Line up the decimal points:
```
  5.25
+ 3.75
------
```
- Add from right to left:
  - 5 + 5 = 10 (write 0, carry 1)
  - 2 + 7 + 1 (carry) = 10 (write 0, carry 1)
  - 5 + 3 + 1 (carry) = 9
- Bring down the decimal point.
  Answer: 9.00 or 9
12.8 + 7.05
- Line up the decimal points (add a zero to 12.8 for alignment):
```
  12.80
+  7.05
-------
```
- Add from right to left:
  - 0 + 5 = 5
  - 8 + 0 = 8
  - 2 + 7 = 9
  - 1 + 0 = 1
- Bring down the decimal point.
  Answer: 19.85
0.67 + 1.3 + 4.25
- Line up the decimal points (add zeros for alignment):
```
  0.67
  1.30
+ 4.25
------
```
- Add from right to left:
  - 7 + 0 + 5 = 12 (write 2, carry 1)
  - 6 + 3 + 2 + 1 (carry) = 12 (write 2, carry 1)
  - 0 + 1 + 4 + 1 (carry) = 6
- Bring down the decimal point.
  Answer: 6.22

Part 2: Subtracting Decimals

9.5 - 4.3
- Line up the decimal points:
```
  9.5
- 4.3
-----
```
- Subtract from right to left:
  - 5 - 3 = 2
  - 9 - 4 = 5
- Bring down the decimal point.
  Answer: 5.2
15.0 - 8.75
- Line up the decimal points (add zeros to 15.0 for alignment):
```
  15.00
-  8.75
--------
```
- Subtract from right to left (borrow as needed):
  - 0 - 5 (borrow from 0, then from 5): 10 - 5 = 5
  - 9 - 7 = 2
  - 4 - 8 (borrow from 1): 14 - 8 = 6
  - 0 - 0 = 0
- Bring down the decimal point.
  Answer: 6.25
7.24 - 3.8
- Line up the decimal points (add a zero to 3.8 for alignment):
```
  7.24
- 3.80
-----
```
- Subtract from right to left (borrow as needed):
  - 4 - 0 = 4
  - 2 - 8 (borrow from 7): 12 - 8 = 4
  - 6 - 3 = 3
- Bring down the decimal point.
  Answer: 3.44

Part 3: Multiplying Decimals

3.5 x 2.1
- Multiply as whole numbers:
```
  35
x 21
----
  35
 700
----
 735
```
- Count decimal places: 3.5 has 1, 2.1 has 1. Total = 2 decimal places.
- Place decimal in the product (7.35).
  Answer: 7.35
0.15 x 0.8
- Multiply as whole numbers:
```
   15
x   8
-----
  120
```
- Count decimal places: 0.15 has 2, 0.8 has 1. Total = 3 decimal places.
- Place decimal in the product (0.120).
  Answer: 0.120 or 0.12
10.3 x 4
- Multiply as whole numbers:
```
  103
x   4
-----
  412
```
- Count decimal places: 10.3 has 1, 4 has 0. Total = 1 decimal place.
- Place decimal in the product (41.2).
  Answer: 41.2

Part 4: Dividing Decimals

8.4 ÷ 0.4
- Move the decimal in the divisor (0.4) one place to the right to make it 4.
- Move the decimal in the dividend (8.4) one place to the right to make it 84.
- Divide 84 ÷ 4 = 21.
  Answer: 21
12.96 ÷ 1.2
- Move the decimal in the divisor (1.2) one place to the right to make it 12.
- Move the decimal in the dividend (12.96) one place to the right to make it 129.6.
- Divide 129.6 ÷ 12:
```
    10.8
  ______
12|129.6
   -12
   ----
     09
     -0
     --
     96
    -96
    ---
      0
```
Answer: 10.8
5.6 ÷ 7
- Divide 5.6 by 7. Place the decimal point in the quotient directly above the decimal point in the dividend.
```
    0.8
  _____
7|5.6
   -0
   --
   5 6
  -5 6
  -----
     0
```
Answer: 0.8