procedure TForm1.Button1Click(Sender: TObject);
begin
  try
    Zensur := StrToFloat(Edit1.Text);
    if Zensur = 1 then Label1.Caption := 'sehr gut';
    if Zensur = 2 then Label1.Caption := 'gut';
    if Zensur = 3 then Label1.Caption := 'befriedigend';
    if Zensur = 4 then Label1.Caption := 'ausreichend';
    if Zensur = 5 then Label1.Caption := 'mangelhaft';
    if Zensur = 6 then Label1.Caption := 'ungenügend';
  except
    Label1.Caption := 'Quatsch!';
  end;
end;