Is 이걸 the same as 이것을?
Yes, it is a common contraction.
이것 -> 이거
이것은 -> 이건
이것을 -> 이걸
이것이 -> 이게
Yes it kinda just gets smashed together the same thing happens with 것은 => 건
Im not sure but i think its an abbreviation.
Now say 이걸 읽어 10 times really fast! It ties my tongue in knots
Precisely why Duolingo included the sentence, I'm thinking.
아기가 이것을 읽어 should be accepted?
Even though the lesson is about casual speech, super polite sentence constructions like: 이것은 어렵습니다 and 아가가 이것을 읽습니다 should still be accepted.
Or, they can be marked wrong as wrong formality level
@Adrian - then how would people learn how to speak with casual conjugations?
Do you mean I am the baby?
Aww, you are so sweet ♥
나는 창문을 열기 것는 더 걱정해요.