Notice of lay-off shall be given to the teacher by registered letter no later than the fifteenth (15th) day of May of any school year. The teacher, within twenty (20) teaching days of receiving notice of lay-off, shall indicate in writing, by registered mail, his/her wish to be placed on the re-employment list. Notwithstanding anything else in this article, failure to respond within the time limit specified shall relieve the onus on the Division for that teacher’s placement on the re-employment list and the teacher shall lose seniority.