This is a great exercise to do just prior to handwriting or other fine motor activities (e.g. using cutlery, doing up buttons, tying shoelaces, threading beads), because it activates the core and upper limb muscles (shoulder, elbow, wrist, hand and fingers).

Seated:
Make sure it’s a sturdy chair. Place your hands on the sides of your chair, halfway between the front and back of the chair (so the chair will stay still and balanced when you lift your bottom). Push down through your hands to lift your bottom off the chair (and feet off the floor also if you can).
Wheelchair:
Make sure the wheelchair brake is on and you position your hands on the middle of your armrests. Push down through your hands to lift your bottom off the chair.
Try holding one foot up off the floor while doing the Chimpanzee Swing
While doing the Chimpanzee Swing, swing your bottom slightly forwards and back, keeping your bottom off the floor.
After doing the Chimpanzee Swing, sweep your long chimpanzee arms back and forth along the floor. Imagine what it would feel like to sweep your long chimpanzee arms across the leaves and vines in the jungle.
For how long can you hold your bottom off the floor in the Chimpanzee Swing position?