Final answer:
It is true that all of a child's skills should be documented, even if not displayed during a session, as it aids in tracking development and planning interventions.
Step-by-step explanation:
The statement that it is best practice to document all of a child's skills, even if they are not displayed during a session, is true. Comprehensive and ongoing documentation is essential in educational and developmental settings, as it allows for a clear understanding of the child's abilities, progress, and areas that may require additional support. This practice is fundamental for informing instruction, designing effective interventions, and ensuring that the child's development is being tracked over time, regardless of whether a specific skill is observed in a given session.