Explain why covering something with a blanket can put out a fire

No oxygen

Explanation:

when something is covered in a blanket it prevents the fire from being able to have any oxygen

Its called smothering the fire

Explanation:

A fire needs three things to burn always: fuel, oxygen, and a heat source. Eventually the heat source will not be an issue, but the oxygen and fuel is. If the fire is small enough throwing a blanket can quite smother it. What happens is it cuts off the oxygen supply the fire needs long enough for it to die out.