Definition: A substance given to stimulate the body's production of antibodies and provide immunity against a disease without causing the disease itself in the treatment, prepared from the agent that causes the disease (or a related, also effective, but safer disease), or a synthetic substitute.

Alright class, settle down, let’s dive in today! Let's talk about “vaccine,” it’s a word you’ve likely heard, A medical marvel, quite frequently stirred. Now the dictionary gives us a detailed decree, So listen closely, and you'll surely see: “A substance given to stimulate your body’s might, To build up defenses, shining ever bright!” It sparks antibody creation, a clever little scheme, Protecting you from sickness – a wonderful dream! It doesn't give you the illness, that's the key, But prepares your system for what it might see. Think of it like practice, a training ground so true, Using a weakened version, or something new. Perhaps the agent that caused the disease you fear, Or a similar challenge, made safer and clear! So, a vaccine is a shield, a proactive plan, To keep you healthy, safe, and strong as can stand! Does anyone have any questions? Don't be shy, let’s discuss!