Often students will complete a task more readily if they feel they have some power or ownership of the task. Building in some choice to the task can achieve this. Make sure the choices you are giving are choices that still support achievement of the outcomes required for the lesson. For example, if it is a handwriting lesson offering talk to text does not achieve the lesson outcome, however if it is a narrative writing task then talk to text is a valid option.
Within reason, allow the student as much autonomy and choice in curriculum activities as possible to minimise the likelihood of teacher-student conflict. Schedule the student as much independent work as possible, i.e. tasks that require them to work alone.
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