The Torah presents the ten plagues as three groups, with each group comprised of three plagues, and the final blow of Makkat B’khorot.
This Friday night begins the holiday of Pesach, when we are commanded from the Torah to celebrate our freedom from slavery in Egypt.
In the beginning of the Haggadah, when we read K’ha Lahma ‘Anya, we highlight the aspect of the Misvah of eating Massah.