One student asked me why we say "eat soup" in English, and not "drink soup". In Japanese, they say "drink soup".
The truth is, there's no grammar rule involved in this. It's just a matter of the speaker's preference. However, it is more appropriate to say "eat soup" because of several reasons. Let's start with the obvious: First, soup is served in a bowl.--not from a drinking glass or cup, so we don't drink it.
Second, we use a spoon or chopsticks to put the soup into our mouths. We don't drink it the way we drink water or beer from a glass or mug.
The same student argued that soup is liquid, so it's more appropriate to drink it instead of to eat it. Oh yeah, he's got a point, but let's remember that soup is food, so we eat it. It's not a beverage like Coke or beer or juice, and this brings me back to my point that it is not served in a drinking glass.
Third, soup is not just plain liquid. Soup means some liquid and some vegetables or meat that we chew and swallow.
But as I mentioned above, there's no grammar rule that governs this. To say "drink soup" is also okay, but "to eat soup" is a lot more popular and more appropriate. It's up to you. Drink your soup if you want, eat your soup if you want. Just make sure not to spill it.