It depends on the child. Some children may find the crucifixion story too scary to hear, while others may be fascinated by it. Each child is different and will respond differently to various stories and images. It's important to use discretion when deciding what is appropriate for each individual child. Some parents choose not to tell their children about the crucifixion at all, while others believe that it's an important part of Christian history and teaching. Ultimately, it's up to each parent to decide what they feel is best for their own child.