Translation:Tomorrow I have geography class.
tomorrow i have geography. would be a common way to say it.
"i have geography tomorrow" should be accepted on the grounds that in English, common nouns, e.g. geography, math, science, history; may be used as names for the classes in which they are taught.
Tomorrow I have a geography class
"I have a geography class tomorrow" should be accepted
When I try to report this there is no option for "The English sentence is unnatural or has an error".