Draw a long horizontal line on the chalkboard -- approximately 2 to 3 feet long, if possible.
Make 3-inch-long vertical lines intersecting the horizontal line. Space the vertical lines evenly along the horizontal line. Each vertical line represents a number.
Label the vertical lines. Start the numbering with the left vertical line (with zero, unless you wish to include negative numbers) and number each vertical line in sequential order.
Create a subtraction problem to solve with the number line. For example, use a problem like, "There were 12 students riding a school bus and five students got off the bus. How many students are left on the school bus?"
Show students how to circle the number 12 on the number line because that is the first number in the number problem.
Jump five spaces backward from the number 12, making an arc between each number on the number line. Stop jumping after five jumps, ending at the number seven.
Circle the number seven and show students that 12 - 5 = 7.
Erase the chalk marks and repeat the same process with a variety of different subtraction problems to illustrate the concept.
Invite students to the chalkboard to practice jumping to solve subtraction problems.