Regardless of age, many factors contribute to how any person, adult or child, works through the grieving process. These factors include:
The closeness of the relationship with those involved.
Age and developmental level. An elementary-age child has a much different level of understanding of death than a high school student.
Support systems in place.
Other concurrent stresses that may exist.
Health (physical and mental). A child who is lower functioning has a much different level of understanding than a child of the same age and of average intelligence.
Circumstances surrounding the death or anticipation of the event.
The timeline involved (i.e., a sudden event as compared to a prolonged illness). Someone who has had the opportunity to prepare for an impending loss may react differently than someone who loses a loved one abruptly.
Previous experiences with death, including the death of pets. A person who has already experienced the death of someone close to them is already familiar with the grieving process as opposed to someone who has not previously dealt with a death.