Decimal Detective: Cracking the Number Line Code!

Mathematics Grades 7th Grade 1:15 Video
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Lesson Description

Learn to place positive and negative decimals on a number line with confidence! This lesson uses a fun detective theme to help you understand how decimals fit on the number line, building a strong foundation for future math adventures.

Video Resource

Placing positive and negative decimals on a number line | Decimals | Pre-Algebra | Khan Academy

Khan Academy

Duration: 1:15
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Key Concepts

  • Number line representation
  • Positive and negative decimals
  • Scale and intervals on a number line
  • Understanding tenths

Learning Objectives

  • Students will be able to accurately place positive and negative decimals on a number line.
  • Students will be able to interpret the scale and intervals of a given number line.
  • Students will be able to estimate the position of a decimal value between two marked points on a number line.

Educator Instructions

  • Introduction (5 mins)
    Begin by asking students what they already know about number lines. Briefly review integers on a number line, then introduce the idea that decimals can also be placed on a number line. Engage students by framing the lesson as a 'Decimal Detective' mission where they need to locate hidden decimal 'clues' on the number line.
  • Video Viewing (7 mins)
    Play the Khan Academy video 'Placing positive and negative decimals on a number line'. Encourage students to take notes on how the presenter determines the location of each decimal. Pause the video at key points to clarify any confusion.
  • Guided Practice (10 mins)
    Work through examples similar to the video, emphasizing the importance of understanding the scale of the number line. Start with simpler decimals (e.g., 0.5, -0.2) and gradually increase the complexity (e.g., 1.7, -0.8). Have students come to the board to demonstrate their understanding.
  • Independent Practice (10 mins)
    Provide students with a worksheet containing number lines with various scales and a list of positive and negative decimals. Students should independently place the decimals on the number lines. Circulate to provide support and answer questions.
  • Wrap-up and Assessment (8 mins)
    Review the key concepts of the lesson. Administer the multiple-choice and fill-in-the-blank quizzes to assess student understanding.

Interactive Exercises

  • Number Line Scavenger Hunt
    Create a large number line on the classroom floor. Provide students with cards containing positive and negative decimals. Students must physically place the cards on the correct locations on the number line. This can be done individually or in teams.
  • Online Number Line Tool
    Use an interactive online number line tool where students can drag and drop decimals onto the number line. This allows for immediate feedback and visual reinforcement.

Discussion Questions

  • How does understanding the scale of a number line help you place decimals accurately?
  • What strategies do you use to determine the location of a decimal between two marked points on a number line?
  • Why is it important to be able to represent decimals on a number line?

Skills Developed

  • Number sense
  • Visual representation of numbers
  • Problem-solving
  • Critical Thinking

Multiple Choice Questions

Question 1:

On a number line, where would you find -0.7?

Correct Answer: To the left of 0

Question 2:

Which decimal is located halfway between 0 and 1 on a number line?

Correct Answer: 0.5

Question 3:

If a number line is marked in increments of 0.2, what would the third mark to the right of 0 represent?

Correct Answer: 0.6

Question 4:

Which of the following decimals is closest to 2 on a number line?

Correct Answer: 2.1

Question 5:

Which number is further from zero? -1.5 or 0.2?

Correct Answer: -1.5

Question 6:

Between which two whole numbers does the decimal -2.4 lie on a number line?

Correct Answer: -2 and -3

Question 7:

On a number line with marks every 0.1, how many marks would you count to get from 0 to 0.9?

Correct Answer: 9

Question 8:

Which decimal represents a point just a little to the left of -1 on a number line?

Correct Answer: -1.1

Question 9:

If you move from 0 to -0.3 on a number line and then move to 0.5. How far did you travel?

Correct Answer: 0.8

Question 10:

A point is located between 1.7 and 1.8, and closer to 1.8. What is a likely value of this point?

Correct Answer: 1.78

Fill in the Blank Questions

Question 1:

On a number line, numbers to the left of zero are called __________ numbers.

Correct Answer: negative

Question 2:

The distance between each mark on a number line is called the __________.

Correct Answer: scale

Question 3:

The decimal 0.5 is the same as one __________.

Correct Answer: half

Question 4:

On a number line, -0.2 is __________ than -0.1.

Correct Answer: less

Question 5:

When placing a decimal on a number line, it's important to first check the __________ of the line.

Correct Answer: scale

Question 6:

The number 1.9 is very close to the whole number __________.

Correct Answer: 2

Question 7:

The further a negative number is from zero, the __________ its value.

Correct Answer: lower

Question 8:

A decimal with a value between 0 and 1 can also be considered a ___________.

Correct Answer: fraction

Question 9:

To accurately place decimals, we must understand ____________ and intervals.

Correct Answer: scale

Question 10:

If you move from 0 to -0.4, you have moved four _________ to the left

Correct Answer: tenths

Educational Standards

7.N.1:Read, write, represent, and compare rational numbers, expressed as integers, fractions, and decimals. Explain and apply the concept of absolute value. 7.N.1.1:Compare and order rational numbers expressed in various forms using the symbols '<', '>', and '='. 7.N.1.3:Explain the relationship between the absolute value of a rational number and the distance of that number from zero on a number line. Use the symbol for absolute value. Apply the concept of absolute value to model and solve problems.

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