Introduce students to percentages by first defining the word. Explain that "percent" means part of 100 and that a percentage is a ratio or fraction of a number over 100. Provide an example of this concept. For instance, a test score of 75 percent indicates that 75 out of 100 questions were answered correctly.
Use word problems to teach percentages, in addition to simple math problems. Create scenarios that interest students and are age-appropriate. For instance, use the following word problem for a class of fifth-graders: "Jake saw six of the eight Harry Potter movies. What percentage of the Harry Potter movies did Jake see?"
Explain that percentages are calculated by cross-multiplication of fractions. Using the problem in the last step, for example, show that the fraction 6/8 is multiplied by 100/1 to calculate the percentage of movies that Jake viewed. Likewise, a percentage is converted back to a fraction when multiplied by 1/100.
Use visual aids to reinforce percentages. Show pie charts, graphs and other images to demonstrate the idea of percentages. Alternatively, use money as a practical example of percentages. These visual and practical scenarios help children to understand what is otherwise a very abstract concept.