Since sex is so prevalent in our society, not to mention necessary for our survival as a species, it is no wonder that we dream of having sex. As with any dream symbol, what sex means to you in your dream will depend on your feelings about sex and your experience as a sexual being.
Dreams about snakes can mean many different things to different people, depending on the type, location, what it is doing and your association with snakes in waking life.
Dreams about school are among the most common dream themes. If you are taking or trying to take a test in school also see the meaning of Exam dreams, which is another common dream theme.
Spiders in a dream may represent different things and will depend on how you feel about spiders. Spider dreams can be either negative or positive in nature. Often a spider is associated with the aspects of feminine energy and therefore may represent a woman in your life. This will likely be a strong, overbearing mother or another powerful woman. It may also represent the archetypal feminine energy within yourself or an aspect of yourself. A spider in a dream may also represent other aspects of the feminine archetype.