Good at or Good in?

Prepositions seem to be the most confusing aspect of English grammar for the speakers of English all around. While many people say ‘she is good at English’, the number of those who say ‘she is good in English’ is also growing. So, which sentence is the correct one?

Practically speaking, it is unwise to say only one of these two sentences is correct. The reason is English language is constantly undergoing a process of being plain, straight-forward and flexible. In spoken English, you may either say ‘good at’ or ‘good in’ as both these prepositions are nowadays interchangeably used by an increasing number of English speakers across the world. However, the standard form appears to be ‘good at’. Therefore, in formal contexts try to use ‘good at’ and in informal English either of the two!

More examples:

John is bad at Mathematics.

Jane is better at French than (at) Spanish.

Sania Mirza is very good at tennis.

The footballer was at his best performance last year.

(The sentences above can also take ‘in’ in the place of ‘at’ though the former (in) is not considered standard especially while talking about one’s ability in a subject. However, by convention, only ‘at’ is widely used with sports and games)