Complex sentence: Inside is Jack's body, with blood everywhere, luckily most of the other students are watching a performance by a magician named Ken (David Copperfield), so they don't what's happening yet.
Split into simpler sentences: Inside is Jack's body, with blood everywhere. Luckily, most of the other students are watching a performance by a magician named Ken (David Copperfield), so they don't know what's happening yet.