One of the easiest ways to teach fractions and percentages is to use money, which works well as currency is often measured in dollar increments, which can be changed to 100 percent. Have children set up "shops," in which some of them sell things and others are buying, giving the buyers a dollar each with which to purchase things; items should cost less than $1. After children have made their purchases, have them identify what percentage of their dollar they spent on the item, then what percentage remains. For an extra step to this game, have them change percents into fractions with 100 as the denominator.
Create basic dominoes with fractions on one end and percentages on the other end, out of basic materials such as cardboard or construction paper. There should be at least 20 dominoes to ensure a game that lasts enough time. The goal is to match percentages to their corresponding fractions, which should be found on different dominoes. Divide the dominoes among the children and have one child at a time try to match as many of her dominoes to what's on the table, letting the following child continue when she has no more options. The first child to get rid of all her dominoes wins.
A simple but effective way of drilling children once they have mastered the basic concepts of fractions and percentages is to provide a series of problems to convert from one to the other. Divide children into groups, being sure to mix in students who have an easier time with the problems with those who have a harder time. Time the groups; the first group to correctly solve all the problems should win a small prize.
A pizza party can provide a great setting in which to turn fractions and percentages into games. Order enough pizzas for your group, but have them cut (or cut them yourself) into different numbers of slices: one can be cut into thirds, one into fourths, and so on. Have children identify the fraction and percentage of one slice in each pizza, then have them find a number with a common denominator that will allow them each to have an equal amount (for example, if you use the pizza in thirds and one in fourths, cutting them each into twelfths will allow students to all have an equal amount).