The Dutch "groot" only refers to size. In English, "my school is great" is unlikely to have that meaning. Beware of false cognates!
OK thanks. although then great should be accepted as it can mean big (as the tool tip says), but I understand why it is not
Yeah, but keep in mind that not all the tooltips are necessarily appropriate for every sentence. In other contexts, great can definitely mean big. "A great amount", "of great importance", things like that.