Classic horror conventions allow the audience to recognise straight away that it is a horror associated film. By using these conventions it plays with their mind/expectations to create a classical horror.
Vulnerable school girl which indicates that she is a victim within the sequence.
The actor/victim is home alone with no parent around which suggests that something bad is going to happen in a secure place - this follows the Wes Craven theory.
A safe place, this is suggest how even in the safest of places, the victim can still be murdered which conveys a contrast between safe and in danger. It also allows the audience to think that nothing is going to happen to the actor due to being in that location however within the film, that observation changes.
Typical stereotyping, we believe that a blonde girl is associated with the word 'dim' therefore when it comes to being killed, they are the most vulnerable and more likely to be killed first.
Paranormal activity is a typical horror convention, it allows the film to play with the human mind into thinking what is going to happen next. It is based on the outside bonds of established science.
Reflection used within a horror allows the scene to become scary and unexpected which is what the audience thrives off.
Ambient sound, this creates a suspension between the actor and the audience due to the scene beginning with low non-diegetic sound which then increases. This indicates to the audience that something bad is about to happen.