For a 6-year-old child with a deformed and swollen forearm due to a fall, what would be the best immediate action?

Applying ice in a plastic bag is the most effective immediate action for a child with a deformed and swollen forearm after a fall. Ice helps to reduce swelling and numb the area, which can provide pain relief. It can also prevent further inflammation that might occur due to injury.

When dealing with a potential fracture or significant injury, the immediate priority is to manage pain and limit swelling. Ice can be applied directly to the injury, ensuring it's wrapped or contained in a plastic bag to protect the skin from frostbite.

This method is commonly recommended in first aid protocols for acute injuries, particularly those involving soft tissue damage. Using ice should be complemented with monitoring the child’s condition, and seeking professional medical attention is important in such cases.