Percentage is the ratio of a part to a whole. More specifically, one part of one hundred. For example 50% is one 50 parts of one hundred. Percentages can be written as fractions, decimals, or percentages. They all translate to the same idea or concept. Percentages can be presented as a pattern of behavior of numbers (parts of a whole).
We should teach our students all parts of percentages, some with more emphasis than others. Students should have an understanding of the several ways percentages can be represented. Students are usually apprehensive about learning about percentages. They know that percentages have something to do with decimals and fractions and they are uncomfortable with either topic. In order to teach percentages effectively, teachers must understand the terms and concepts associated with them (fraction, ratio, decimals, etc.).
One way to relay percentages to students is to present a whole item. Take a part of the whole and discuss the remaining part or the part taken. Both can be represented as a fraction, decimal, and then a percentage of the whole. I repeatedly use this type of example to help my students understand the concept of percentages and their usefulness.
How do you teach percentages to your students? Is your method different for each grade level you teach?