This comments are very helpful about the physical state of the soup between 0 and 100 degrees C. But I still dont understand the gramatics. My answer the children are eating the soup is wrong by Duo. So why the present tense is not correct. Why the children eat the soup (like every day)
We "eat" soup because it usually has meat and/or vegetables in it which have to be chewed. If it were only a broth and we lifted the bowl up to our lips, or if the broth were in a cup which we raised to our lips, we then would be drinking it. But, if the broth were in a bowl, and we used a spoon to get the broth to our mouths, we would say we are "eating" the broth.
I thought it was the children eat soup but it the children are eating soup
No. Both of those translations are incorrect, since the German sentence has die Suppe ("the soup") and not Suppe ("soup").
So you can say "The children eat the soup" or "The children are eating the soup".