The book of Vayikra, and this first aliyah, begins with G-d calling (the word "Vayikra") Moshe Rabeinu to the Mishkan, and giving details of the procedure of giving animal sacrifices. This parsha is traditionally the first one learned by small children when they begin their Jewish studies and they are shown the small letter alef in the first word "Vayikra". Several commentaries say that the alef is small to indicate the humility of Moshe.