* The air we breathe: The atmosphere is about 21% oxygen.

* Water: Oxygen is a component of water (H₂O).

* The Earth's crust: Oxygen is the most abundant element in the Earth's crust, found in minerals like silica (SiO₂) and iron oxides (like rust).

* Living organisms: Oxygen is essential for respiration in most living organisms, including plants and animals.

* Many compounds: Oxygen is found in many other compounds, such as carbon dioxide (CO₂), sugar (C₁₂H₂₂O₁₁), and proteins.

It's important to note that oxygen is not just "in" things, it's often *bonded* to other elements to form molecules and compounds.