Decimals in Disguise: Cracking Word Problems!

Mathematics Grades 7th Grade 1:33 Video
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Lesson Description

Learn to confidently tackle decimal addition word problems by identifying key information and aligning decimals for accurate solutions. This lesson will sharpen your problem-solving skills and reinforce your understanding of decimal operations.

Video Resource

Adding decimals word problem | Decimals | Pre-Algebra | Khan Academy

Khan Academy

Duration: 1:33
Watch on YouTube

Key Concepts

  • Decimal Addition
  • Word Problem Interpretation
  • Identifying Relevant Information
  • Aligning Decimals

Learning Objectives

  • Students will be able to identify the necessary information within a word problem to solve for decimal addition.
  • Students will be able to correctly align decimals when adding multiple decimal numbers.
  • Students will be able to solve decimal addition word problems accurately.

Educator Instructions

  • Introduction (5 mins)
    Begin by briefly reviewing decimal place values (tenths, hundredths, etc.) and the importance of aligning decimals when adding. Engage students by asking them about real-world scenarios where adding decimals might be necessary (e.g., calculating grocery bills, measuring ingredients).
  • Video Viewing (7 mins)
    Play the Khan Academy video 'Adding decimals word problem' (https://www.youtube.com/watch?v=c4fUaD4g4mc). Instruct students to pay close attention to how the problem is set up and solved.
  • Guided Practice (10 mins)
    Work through a similar word problem on the board, emphasizing the steps: 1. Read and understand the problem. 2. Identify the numbers to be added. 3. Align the decimals. 4. Add the numbers carefully. 5. Write the answer with the correct units.
  • Independent Practice (10 mins)
    Provide students with a worksheet containing 3-4 similar word problems. Have them work individually to solve the problems. Circulate to provide assistance as needed.
  • Review and Wrap-up (8 mins)
    Review the solutions to the independent practice problems. Address any remaining questions or misconceptions. Summarize the key steps for solving decimal addition word problems.

Interactive Exercises

  • Decimal Alignment Game
    Create a digital or paper-based game where students must correctly align decimals before adding them. This can be a timed activity to increase engagement.
  • Word Problem Creation
    Have students create their own decimal addition word problems and share them with the class. This encourages deeper understanding and creativity.

Discussion Questions

  • Why is it important to align the decimal points when adding decimals?
  • What strategies can you use to identify the relevant information in a word problem?
  • Can you think of a time you've used decimals in your daily life?

Skills Developed

  • Problem Solving
  • Critical Thinking
  • Decimal Arithmetic
  • Reading Comprehension

Multiple Choice Questions

Question 1:

What is the first step in solving a decimal addition word problem?

Correct Answer: Read and understand the problem

Question 2:

Why is it important to align the decimal points when adding decimals?

Correct Answer: It ensures you add the correct place values

Question 3:

What is 4.56 + 2.1?

Correct Answer: 6.66

Question 4:

Sarah buys a book for $6.75 and a pen for $2.50. How much does she spend in total?

Correct Answer: $9.25

Question 5:

John runs 3.2 miles on Monday and 2.75 miles on Tuesday. How many miles does he run in total?

Correct Answer: 5.95 miles

Question 6:

Which of these is an example of a word problem?

Correct Answer: If a toy costs $5.50 and tax is $0.50, what is the total cost?

Question 7:

What should you do with unnecessary information in a word problem?

Correct Answer: Ignore it

Question 8:

What does 'total' usually imply in a word problem?

Correct Answer: Addition

Question 9:

0.75 + 0.25 = ?

Correct Answer: 1.00

Question 10:

A recipe calls for 1.25 cups of flour and 0.75 cups of sugar. How many cups of ingredients are needed in total?

Correct Answer: 1.75 cups

Fill in the Blank Questions

Question 1:

When adding decimals, it is important to ________ the decimal points.

Correct Answer: align

Question 2:

In the video, the length of Nadia was considered __________ information.

Correct Answer: unnecessary

Question 3:

7 plus 4 hundredths equals _________ hundredths.

Correct Answer: 11

Question 4:

The total weight of the babies was _________ pounds.

Correct Answer: 15.61

Question 5:

Before adding, you should always __________ and understand the word problem.

Correct Answer: read

Question 6:

If one item costs $3.50 and another costs $4.25, the ______ cost is $7.75.

Correct Answer: total

Question 7:

The first step is to _______ the decimals.

Correct Answer: align

Question 8:

__________ information distracts you from solving the problem.

Correct Answer: Unnecessary

Question 9:

Always write the answer with the correct __________ .

Correct Answer: units

Question 10:

0.3 + 0.7 = __________

Correct Answer: 1.0

Educational Standards

7.N.2.5:Model and solve problems using rational numbers involving addition, subtraction, multiplication, division, and positive integer exponents. 7.N.1:[Standard] Read, write, represent, and compare rational numbers, expressed as integers, fractions, and decimals. Explain and apply the concept of absolute value.

Teaching Materials

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