Vlookup()Vlookup() should work. With the Student names in column A, row 1 has the labels, start this formula in cell B2 and copy down
=vlookup(A2,SheetB!$A$1:$B$100,2,false)
=vlookup(A2,SheetB!$A$1:$B$100,2,false)
This is on the assumption that the grades are listed on a sheet called SheetB. Adjust sheet names and ranges as required.