Final answer:
When assisting a resident with a weak side to sit up and dangle their legs, a CNA should be on the resident's weak side to provide necessary support for balance and safety.
Step-by-step explanation:
When a Certified Nursing Assistant (CNA) is instructed to have the resident sit up and have him dangle his legs, and the resident has a weak side, the CNA should be positioned on the resident's weak side. This is because the resident will need more support on their weaker side to aid in balance and prevent potential falls. As such, the CNA should be ready to provide assistance by being on the side where the resident exhibits weakness.
Considering the patient's report of feeling pins and needles in his left arm and leg and difficulty in sensing touch with a pen on the same limbs, the weak side is likely the left one. This indicates a problem with sensory systems or possible neurological issues. In such cases, being on the patient's left side would give them the necessary support as they attempt to sit up and dangle their legs from the bed.