Let them use models to clean and brush like teeth and make them dirty so they understand how many germs there are and show them a model of how if you don't put deodorant on they will stink and then let them make one up becuase from one teen to another I love it when teachers ask us something or for us to make a decision
It takes about 90 days so that the antibodies can get in action. This process is known as seroconversion and antibodies are not produced right after the person has been infected.