Here's why:
* It's not a singular thing: You can't point to "tea" and say "that's tea." Tea is a type of drink made from a plant, and there are countless cups of tea, tea bags, and tea leaves.
* It describes a substance: "Tea" refers to the dried leaves of the Camellia sinensis plant, which are used to make the beverage.
* It can be measured: You can buy a pound of tea, a box of tea bags, or a cup of tea. This further demonstrates that it's a material substance.
Contrast with a concrete noun:
A concrete noun, like "cup," refers to a specific object that you can touch and see.
In summary: "Tea" is a material noun because it refers to a substance, not a specific object.