Begin each class with an example or "warm up" activity that incorporates a portion of the key concept while at the same time grabbing students' attention. For example, open a class on percentages by having each student list all the television programs he or she watches and the number of hours watched each per week, then have the students add up the total number of hours they spend watching TV in a week.
Walk students through the process of applying the concept once you have their attention using a tangible example that applies to their lives. For example, explain to students that if you spent two out of 10 TV hours per week watching "Golden Girls," you watch "Golden Girls" 2/10 of your time -- or in other words, 20/100 or 20 percent.
Place the students into small groups and have each formulate a different scenario where they can apply the concept. Make yourself available as students talk amongst themselves to offer ideas. If one group seems to have reached a dead end, ask questions that lead them to discover answers for themselves. If you're teaching teenage or adult students, for example, you might want to ask them how they spend each paycheck from their part-time jobs.
Have each small group present their findings to the class if time permits. By involving students not only in learning but also teaching, you give each a personal incentive to excel and success -- and, more important, you instill them with confidence.