Here's why:

* It's already oxidized: Burning is a chemical reaction where a substance combines with oxygen. Sodium oxide is already the product of the reaction between sodium and oxygen.

* Stable compound: Sodium oxide is a relatively stable compound, meaning it doesn't readily react with oxygen further.

However, what you may be thinking of is the reaction of sodium metal with oxygen:

* Sodium and oxygen: Sodium metal (Na) is highly reactive with oxygen in the air. When exposed, it rapidly oxidizes, producing sodium oxide (Na₂O) and releasing heat and light. This reaction is so exothermic that it appears as burning.

In summary: Sodium oxide is the *product* of burning sodium, not something that burns itself.