"The child hides under the table."
Translation:아이가 식탁 밑에 숨어요.
The example that Duolingo uses in the tips and notes is:
•물고기가 바다 밑에 삽니다. ― Fish live at the bottom/lower part of the sea. •물고기가 바다 아래에 삽니다. ― Fish live literally under the sea; in the crust, mantle or core of the earth.
But in this example either 아래에 or 밑에 would be acceptable....
Both 밑에 and 아래에 are used to depict "under" or "beneath," though, interestingly, in the Naver dictionary, each is listed as a noun. It would be interesting to get a native's perspective on "에서" in this case. I believe there is a fine nuance between focusing on the place as a place to hide, in which case 에 would be the locator particle. But if focusing on the actual hiding, then 에서 would be used, and it would probably translate " The child is hiding under the table."