As previously suggested, you might need to process singular & plural forms alike:
Code:
Sub BulkFindReplace()
Application.ScreenUpdating = False
Dim FList As String, RList As String, j As Long
FList = "School,Library,Technical,Mathematics,Physics,Chemistry,students,student,teachers,teacher"
RList = "Sch,lib,Tech,Maths,Phys,Chem,stdnts,stdnt,tchrs,tchr"
With ActiveDocument.Range.Find
.ClearFormatting
.Replacement.ClearFormatting
.Format = False
.Forward = True
.MatchCase = False
.MatchWholeWord = True
'Process each word from the Find/Replace Lists
For j = 0 To UBound(Split(FList, ","))
.Text = Split(FList, ",")(j)
.Replacement.Text = Split(RList, ",")(j)
.Execute Replace:=wdReplaceAll
Next
End With
Application.ScreenUpdating = True
End Sub