A compass is a simple instrument. It reads the magnetic forces of the earth and points to magnetic north. If you get it too close to another magnet, it can give you a false reading. In the hands of a skilled scout, it can help keep you on the right path.
In the Scout Oath, we promise to be morally straight. Like the needle of a compass, our morals guide us on the paths of life. There are influences giving you false information, but if you remain true to the morals you have learned from parents, church leaders, and scouting, you can keep on the correct path.
This is a very simple lesson. You can talk about people trying to influence toward drugs, violence, alcohol, etc.