Instructive case
In grammar, the instructive case is a grammatical case used in Finnish, Estonian, and the Turkic languages.
Uralic languages
In Finnish, the instructive case is used to indicate means, manner, instrument, location, or time. It is almost exclusively used in fixed expressions, such as in omin silmin. However, the instructive is productive for infinitive verbal constructions to indicate manner, as in nauraen : He astuivat nauraen sisään.In modern Finnish, many of its instrumental uses are being superseded by the adessive case, as in minä matkustin junalla.
The instructive case is only marginally present in Estonian in lexicalized expressions. Language reformers of the 20th century did try to revive it, but with little success.