Some ways to make the lesson more relevant would be to: Focus on what personal lessons they can take away from what you’re talking about. Ask what it means to be “under the blood on the door posts” today. How can we get under the blood?
Visit a local synagogue (if there is one in your area). Arrange beforehand with the rabbi there, and ask him to explain to the class his understanding of the meaning of the Passover.
Think about what changes the students need to make to their lives as a result of what they have learned. Try to make the lesson as practical as possible. What have they have learned that can improve how they live? How, then, can they make those changes in their own lives?