Attach a 30-inch piece of painter's tape to the floor of the classroom to serve as a number line, and position yourself so that the line is horizontal. Label one end with a "0" and write numbers 1 inch apart in order beginning with "1" until the number "30." Alternatively, adapt the technique for each individual student to make his own 12-inch number line across his desk. If you have an abundance of space in your classroom, make a 50- or even a 100-inch number line on the floor with tape.
Give the class an addition problem. Instruct each student to find the first number of the problem on the number line and point to it. Count the number of spaces to the right that coincides with the second number in the addition problem. The ending number reveals the sum. For example, for "15 + 5," place your finger on the number "15" on the number line and move your finger five spaces to the right to end at "20," which is the correct answer.
Teach subtraction by instructing the student to point to the first number from a subtraction problem on the number line and count the number of spaces to the left that coincide with the second number. The number that the student is pointing to after moving the second number of spaces to the left is the answer to the problem. For example, for "14 - 3," find the number "14" on the number line. Students move their fingers three spaces to the left and end on the number "11," which is the correct answer.
Measure different items in inches using the desk number lines. Hold a pencil, a paper-clip, a pair of scissors and a piece of chalk up to the number line to gain its accurate measurement. When constructing the number line, the accuracy of the space between each labeled tick mark is crucial. The number line, then, acts as a stationary ruler.
Reinforce the concept of "place value" by cutting 3-inch pieces of common drinking straws and instructing students to place one on each numbered mark on the number line. To find the place value, students must count the straws, one at a time, and group them in bunches of 10 with a rubber band to find how many groups of "tens" there are. Then they count the extra straws for the numbers used in the "ones" place.
Teach skip-counting using the number line on the floor by instructing students, one at a time, to jump from the "0" to the "10" mark, and then to the "20" when counting by 10. Students take tip-toe steps when counting by two and take a normal stride when counting by 5. Challenge the students to count by 25 and use a long-jump technique.