Placing Negative Numbers on a Number Line

Now that the students have created their own number lines and acquired an initial understanding of negative numbers, it is time to deepen that understanding by having them explore them further.

Materials: The number lines students created in the first lesson

• Say: Take out your number lines, because we are going to use them to answer some questions.
  What two numbers are 5 units from zero?
  Which number is farther from zero, 7 or 5?
  Explain. Students should that 5 and 5 are five units from zero and that 7 is farther from zero than is 5.
• Ask: What two numbers are 5 units from 2?
  What two numbers are 7 units from 3?
  Students will respond 7 and 3 and 10 and 4, respectively.
  Ask several other questions in which students identify numbers which are some set distance away from a given number.
• Ask: What is the number 9 units to the left of zero?
  What is the number 7 units to the right of zero?
  What is the number 6 units to the left of 2?
  What is the number 5 units to the right of 8?
  What is the number 10 units to the right of 4?
  Questions like these and the ones above will prove helpful when they are finding the difference between two numbers such as 4 – 5.
• Draw a number line with some of the numbers missing like the one shown below.
  

• Ask: (Pointing to each missing number) What is the name of this number?
• Draw several other number lines like the one above which use a scale other than one. Ask the students what some of the missing values are on the number lines you draw. This is a very helpful skill when graphing numbers which vary greatly in size, because using a scale other than one for each mark is quite often needed.

Wrap-Up and Assessment Hints

Create several true and false statements and have the students use their number lines to tell you whether the statements are true or false.

The number 4 is 6 units to the right of 3. (False)
The number which is 8 units to the left of 3 is 5. (True)
The number 8 is to the left of 4. (True)
4 and 3 are seven units apart on the number line. (True)
All negative numbers are to the right of zero on the number line. (False)

Placing Negative Numbers
on a Number Line

• Introducing the Concept
• Developing the Concept

Adding and Subtracting
with Negative Numbers

• Introducing the Concept
• Developing the Concept