No. Ain't is a slang term, so the only dictionary you could find it in would be one that includes slang terms
Aint is a word, but it is not correct English. Yes, learned it myself. Yes, I know that you are suprised.
The word 'aint' is a slang term, derived from word "isn't:" the word 'aint' is used due to laziness and a lack of enunciation of the individual components of the word.
I will go to school today.
I had to rush to get to school today.
Today we learned about osmosis in school
The correct word to fill in the blank is "are." The complete sentence would be "We are going to school today." This indicates that a group, including the speaker, is currently on their way to school or has plans to attend school today.
Today at school there was a two-hour delay.
There me be a longer one, but it aint sky. It is rythm.
the homework we had today was optional because we were really good in school today ......but still everyone did it
'Today I went to the School's canteen to buy dinner'.
"Since today is tomorrow is Monday, we have to go to school."
Yes, if it's part of the name. "I attend the Hawthorne School." If the word "school" is not used as a proper noun, then don't capitalize it. "I will be late for school today."