Appendicitis is a common condition in children 6-17 years of age, and the top reason for emergency surgery in Canada. Children with appendicitis can have very bad pain in their belly. Children often need pain medications given to them through a needle in their arm called an intravenous (IV). The most common IV pain medication is a type of opioid called morphine. We know that opioids work well to improve pain, but there are risks and side effects when taking them. There are non-opioid medications that doctors can give to patients, like ketorolac. Ketorolac helps decrease inflammation and pain and has fewer side effects when a patient takes it for a short period of time. Our past and present overuse of opioids, driven by an unproven assumption that opioids work best for pain, resulted in an Opioid Crisis and doctors are now looking for alternatives. To do this, we need to prove that there are other options to treat children's pain that are just as good as opioids, with less side effects. The goal of our study is to discover if school aged children who arrive at the emergency department with belly pain, improve just as much with ketorolac as they do with morphine. To answer this question, we will need a very large number of patients in a study that includes several hospitals across Canada. With a flip of a coin, each participant will either get a single dose of morphine or a single dose of ketorolac. To make sure that our pain assessment is impartial, no one will know which medicine the child received except the pharmacist who prepared the medicine.