If you are teaching in a religious school, then you have the ability to incorporate morals from that particular religion into your classroom. For example, in a Hebrew school, you would have a lesson plan on the Ten Commandments. In a Christian school, students will learn about the Golden Rule and the Beatitudes. Ask the students for examples of how they can live out these rules and commandments in their everyday lives.
A well-known and popular program for teaching students about the issues of drugs and alcohol is Drug Abuse Resistance Education (D.A.R.E). You can also bring smaller components of this program into your daily life. Explain how drugs and alcohol affect moral issues such as the ways they alter decision-making skills, how abusing drugs can hurt ties with family members or how drinking can make people engage in immoral behaviors such as promiscuous sex or drunk driving.
Instead of having a separate lesson on morals, incorporate them into other disciplines. For example, read a selection of short stories or fables aloud to a class of young children, and have them identify the moral in the story. In a history class, have the students research the morals of a specific group of people, such as the Native Americans or the Pilgrims, and how those morals guided and shaped their lives.
In a morality class or a psychology course, explain the different ways that morals came to be developed. For example, you could look at Kohlberg's Theory of Moral Development and "In a Different Voice" by Carol Gilligan. Make a list of the differences and similarities between morals in the eyes of these two people. Explain the motivations that people have for developing different structures of morals, and look at the morals in place in the students' society today.