change cells on cell change

I have this code

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
If Target.Address = "$b$3" Then
    Sheets("Sheet2").Range("a1:a5") = Sheets("Sheet2").Range("b1:b5")
End If
End Sub

When cell b3 is changed i want to replace what is in a1:a5 with what is in b1:b5

any ideas?