To objectify someone is to treat them as an object rather than as a human being. If your teacher thinks children should be seen and not heard, you might say he objectifies kids.
There are many different ways to objectify a person, including forcing them to be silent, focusing on just their physical body and not their mind, or implying that their appearance or outward beauty is the only important thing about them. You can also use this verb's original meaning, "to take something abstract and make it concrete." Artists objectify abstract feelings and emotions by turning them into physical works of art, for example.