A good starting point for a lesson in negative integers is to draw a line with a zero in the center. To the right of the zero, write positive integers from 1 to 9, and to the left of the zero, write negative integers from -1 to -9. Explain to students that the numbers to the left are negative integers because they are below zero. You can relate this to a tangible concept like temperature since students may be familiar with temperatures below zero.
When teaching negative integers, the next process is to add two negative numbers together. Explain that when two negative integers are added, the result will always be below zero. It may help to explain that when a negative integer is added, it is really subtracted from the integer it is added to. For example, if you were to add -3 to -2, this would end up being -5 since both integers are negative. If this problem subtracted -2 from -3, the result would be -1.
Once the students understand how two negative numbers work together, you can begin to explain how negative integers are added to positive numbers. For example, you can give the students a positive integer like 4, and ask them to add 4 and -2. Since the addition of a negative number results in subtraction, the answer would be 2. Ask what the result would be if you subtracted -2 from 4. In this case, the answer would be 6.
Another important concept with negative and positive integers is multiplication. Begin by explaining to students that two negative integers multiplied together will produce a positive number because the two negatives cancel one another out. However, a negative integer multiplied by a positive number will always produce a negative answer, because only one negative number is present. The negatives will not cancel one another, so the answer will be less than zero.