Here's why:

* Tissues: Groups of similar cells that work together to perform a specific function (e.g., muscle tissue, nervous tissue, connective tissue).

* Organs: Structures made of different tissues that work together to perform a more complex function (e.g., the heart, lungs, stomach).

Example: The heart is an organ composed of:

* Muscle tissue: For pumping blood

* Nervous tissue: To regulate heart rate and rhythm

* Connective tissue: To provide structure and support

Let me know if you want more examples or explanations!