Final answer:
The accurate step in the education plan for using an incentive spirometer is to instruct the patient to inhale slowly and deeply through the mouthpiece without using the nose.
Step-by-step explanation:
The accurate step that should be included in the education plan for using an incentive spirometer is to instruct the patient to inhale slowly and as deeply as possible through the mouthpiece without using the nose. This step ensures that the patient is using the incentive spirometer correctly, allowing for maximum lung expansion. Inhaling through the nose instead of the mouthpiece may not provide accurate results or effectively improve lung function.