Final answer:
Parents are typically the ones to fill out forms concerning a child's adaptive behaviors, but teachers and other informants can also contribute valuable insights.
Step-by-step explanation:
When it comes to filling out forms concerning a child's adaptive behaviors, it is most common for a parent, guardian, or another primary caregiver who has extensive knowledge of the child’s everyday behavior to complete these forms. It can also be beneficial for a teacher or another informant such as a therapist or a childcare provider to provide their perspective, especially if they spend a significant amount of time with the child in different settings. The information collected from these various sources contributes to a comprehensive understanding of the child's adaptive behaviors across different environments.