This powerpoint takes students through natural numbers, whole numbers, integers, rational numbers, irrational numbers, and real numbers.
Please check out the preview that shows how the powerpoint demonstrates rational numbers are the quotient of two integers and how that relates to decimals.
The end of the powerpoint takes the class through some classification problems. The class is given a number and they state the sets of numbers to which that number belongs.
I have found this powerpoint to be very effective in teaching this topic!