Begin by drawing a number line on the right side of the board (it can have any numerical values -- for example, you could do 0-5 or 0-20). Make sure to label the start as zero. Explain to the students that they are going to be learning about the other side of the number line, the area behind the zero. Add an opposite half to the number line with matching negative numbers appropriately labeled.
Have students Think-Pair-Share and discuss how negative numbers might be used in the real world. What are some situations that can be represented by a negative number? Look for answers like overdrafting a bank account, freezing temperatures, or elevation below sea level. Explain that negative numbers can be used to represent the opposite of a positive number situation.
Have all the students push their chairs back and stand in front of them. List several situations or integers and have the students jump if it's positive or sit if it's negative.
- You find $5
- You dove 7 meters
- 10 degrees above zero
- 12 steps backward
- The elevator went down 4 floors
- A loss of 8 yards in football
- 40 ft. below sea level
- You withdraw $52
In closing, ask students what value is represented by their standing position (zero). Remind them that we don't use a symbol for positive numbers.