Final answer:
To assess plantar flexion, the nurse should instruct the client to 'Point your toes downward toward the floor.' This action is part of the range-of-motion exercises that involve the joint of the ankle.
Step-by-step explanation:
To assess plantar flexion of the feet, the nurse should provide the instruction 'Point your toes downward toward the floor.' Plantar flexion involves lifting the heel of the foot from the ground or pointing the toes downward, which is a movement at the joint of the ankle. It is a common motion involved in actions such as standing on the toes or foot-tapping. On the other hand, the action of lifting the front of the foot upward towards the shin is known as dorsiflexion, and rotating the ankles in a circular motion involves inversion and eversion. Moving the feet side to side does not accurately test for plantar flexion.