While the core features of ADHD (attention deficit hyperactivity disorder) have to be prolonged and present in different situations there can be marked changes of the visible symptoms or adaptation to a specific situation as a consequence of the specific situation or individual interests and coping facilities.
Usually ADHD children do better in one-to-one situations, in new or competitive situations (like video games, sport competition) or if they can get an immediate reward for their efforts.
Many parents say that their children have less problems to complete their tasks (homework), if someone is in the room to supervise them. This could help the children to focus and reduce the risk of daydreaming.
Some children need rather specific situations, like background music, or have less problems if they get help from a friend who takes notes of the school day.
Controversially those with ADHD manifest more problems in group settings because they have problems to track conversations. Any boring work will not be completed in a reasonable time span if not supervised and rewarded in an appropriate way.