Step One: Introduction to Concept
Using the sample number line on display in the classroom as reference, ask students to share their previous experiences with using number lines. Share with students the benefits of using a number line as a visual tool. Call on student volunteers, and ask them to walk up and point with meter sticks to verbally given numbers on the number line.
Step Two: Creation of Basic Number Line
Using meter sticks or rulers, have students draw their own number lines with pencil, labeling the numbers ranging from -20 to 20 on the line if there is room (if not, use a smaller range such as -10 to 10). Students will need to choose two colors: one to represent the positive side of the number line, and one to represent the negative side. Students should be encouraged to choose colors that are opposite in nature (such as red and green, yellow and purple, or blue and orange) to strengthen the visual impact of the finished piece.
Once students have chosen their colors, they will begin tracing over the numbers on the line accordingly, leaving zero the color of the pencil to represent that it is neither positive nor negative. When complete, students should clearly see all of the numbers to the left of zero labeled with the “negative" color, and all of the numbers to the right of zero labeled with the “positive" color.
Step Three: Adding Color Dots
To complete the number line, students will again trace over the numbers with corresponding colors, this time adding a dot above the number to represent the spaces away from zero that number sits. There will be more dots above the numbers further away from zero, demonstrating visually how many spaces each number sits away from zero on the number line.
Step Four: Opposites Chart (optional)
If time permits, ask students to list numbers and their opposites, representing them both with written numbers and dots and using the same colors to represent positive or negative placement on the number line.
After number lines and charts are completed, lead a brief discussion with students asking them to share how they can use their number lines to help them identify given positive and negative numbers.
Assessment: Collect number lines and pair charts, and grade them for clarity and accuracy.
Extension: Ask students to use their number lines as visual tools in further lessons to help them locate numbers, identify opposite pairs, and find absolute value of numbers on the number line.