There are several components in this activity. They are:
The student - seated or positioned in a safe position where they can easily see and hear the activity
The switch - suited to the student's needs - for example a jelly bean switch could be placed on a wheelchair tray in front of the student
The power pack device - this is attached to both the switch and the electronic device used for your activity and is used to provide a means for helping the student to access electronic equipment that may otherwise may not be safe or appropriate for them to use. For example, a student with athetoid cerebral palsy may have significant arm movements which would make it dangerous to have a blender placed directly on their tray. With the power pack, they are able to be a safe distance away from the blender (or other tool) but still have direct control over when it is turned on and off.
The electronic device - this can be whatever suits your activity purpose and goals - a toy, a cooking tool, a light or a musical instrument. Ensure it is safe, in good condition and able to stand up to being turned on and off several times during the activity.